Hydroponic lettuce with a dark period grows stronger without overgrowth.

I have been conducting a personal experiment to see how the growth of lettuce changes with different light exposure times.
After sowing, germinating, and growing seedlings in plastic containers, I had to end the experiment when the lettuce grew too large to fit in the containers, but in the end, I felt that the lettuce I gave a dark period grew healthier.
Here is a video.

This experiment is a sequel to the article “Hydroponic lettuce seedling growth rate and germination rate changes with light exposure time”.
The lettuce that was exposed to a lot of light grew a lot, but many of them were overgrown, and as a result, the 16-hour lettuce with an 8-hour dark period seemed to grow healthier.
The following are the observations.

Thinning out the seedlings that were exposed to 16 hours of light and those that were exposed to 24 hours of light.

Fifty seedlings of 16 hours and 24 hours each, which were germinated with germination treatment and grown in the container with nutrient solution, are now growing step by step.


As the lettuce leaves seemed to be overlapping each other, I took out the seedlings that were not growing well from each container and replanted them in another container.


I selected about 20 seedlings of lettuce that had been growing well for 16 hours and 24 hours each, and replanted them at intervals.

Of the 20 seedlings grown in the 16-hour irradiation, half of the 10 seedlings will be grown again in the 16-hour irradiation.
The remaining 10 seedlings will be grown in the 24-hour container.
Also, for the 20 seedlings grown in the 24-hour irradiation, half of the 10 seedlings will be grown in the 16-hour irradiation and the rest in the 24-hour irradiation.

The lettuce with a dark period grew better without overgrowth.

The lettuce seedlings that were grown in the 24-hour period grew larger leaves in both the 16-hour and 24-hour containers.
As for the roots, the lettuce that was exposed to light for longer seemed to have more roots.
I thinned out the lettuce and observed the growth for a few days, but the leaves grew so much that they overlapped even after thinning out, so I ended the experiment.
In terms of the size of the lettuce alone, the lettuce that had been exposed to the light for 24 hours grew larger, but the stems also seemed to have grown longer at the same time.
In other words, they became overgrown.
On the other hand, the lettuce that was repeatedly exposed to light for 16 hours after germination, followed by 8 hours of rest in the dark, looked inferior to the 24-hour lettuce in terms of growth, but the leaves were coming out from the root and seemed to be growing healthily.
If I’m going to let my lettuce grow long without resting for 24 hours, I want to let it rest for 8 hours to make it healthy.
France hydroponics related


Growth and germination rates of hydroponic lettuce seedlings vary with light exposure time.

When growing lettuce from seed in hydroponics, I was wondering how much light I should expose it to after it germinates to speed up its growth, so I experimented.

Lettuce seems to be a long-day plant and needs a moderate period of darkness, so we prepared 50 seedlings each of lettuce that was not exposed to light between 9:00 p.m. and 5:00 a.m. (16-hour lettuce) and lettuce that was exposed to light all day (24-hour lettuce), and observed the growth process.
Fifteen days have passed since sowing, and although there are individual differences, we can conclude that the 24-hour lettuce grew 1.5 to 2 times larger on average than the 16-hour lettuce.
I’ll explain the results in order.

Germinate lettuce seeds by germinating them in the vegetable compartment of the refrigerator.

I used regular sunny (leaf?) lettuce seeds that I bought at a 100-yen store. Lettuce seeds.
I put moistened kitchen paper in a plastic case, scattered the seeds on the paper, covered it with a lid, and stored it in the vegetable room.

It is said that by storing the lettuce in a dark and damp place, the lettuce seeds will think they are planted in the soil and will germinate. I’m sorry if I’m wrong.
The next step is to sow the germinated seeds into the sponge medium.

Prepare seedling containers and lights for the same conditions.

Before sowing, we made containers for seedling growth.

There are four LED bulbs attached to the back of the lid.
The inside is filled with water, and Otsuka House’s concentrated liquid fertilizer is added to keep the EC value at 1.3. The air pump is branched to bring in oxygen.

The only difference is that the outlet in the left container has a smart plug engaged in it, and as mentioned earlier, the lights go off between 9pm and 5am, and it is completely dark inside.

Start seedling growth by floating a styrofoam with sponge medium set on it.

The germinated seeds are then sown into the sponge medium.

Plant the germinated seeds one by one in the middle slit of a sponge filled with water.
In the photo, I used a special sponge, but you can also use a cut-up 100-yen dish sponge.
I was thinking of using special seedling pots to make replanting easier, but I didn’t have enough pots for 100 seedlings on each side, so I just sandwiched them in the styrofoam.
We floated the styrofoam on the surface of the water mixed with nutrient solution and started to grow seedlings.

The germination rate and growth rate differed depending on the exposure time of the light.

After about 10 days, I guess, I started to see a gradual difference in growth.

On the left is a container of 16-hour irradiated lettuce and on the right is 24-hour lettuce.
It is a little difficult to see in the photo, but the lettuce that has been exposed to light for 24 hours is growing larger.
At the same time, however, there were many seeds that had not germinated.
In concrete terms, 35/50 (70%) of the seedlings germinated, while the remaining 15 seedlings did not produce any leaves.
On the other hand, the lettuce seedlings irradiated for 16 hours on the left had a germination rate of 42/50 (84%), although the growth rate was inferior to that of 24 hours.
Since the seedlings are still young, we don’t know how they will change in the future, but it may be better to continue to expose them to light if we want to grow larger seedlings, and to provide a dark period if we want to increase the germination rate.

Future growth experiments

I will be experimenting to see if a dark period or a 24-hour period is better for growing strong plants without overgrowth.
I also bought a plant growth light, so I’d like to see how much the growth rate changes with regular LED bulbs.

Solving the lack of oxygen caused by rising water temperature by making the water surface ripple [Hydroponics].

Have you ever experienced a sudden loss of vigor in your hydroponic vegetables that were growing well until recently?
The reason may be that the temperature of the water circulating in the hydroponics equipment has risen along with the rise in temperature and room temperature, and the amount of oxygen dissolved in the water has decreased.
As the temperature of the water rises, the amount of dissolved oxygen decreases, and if there is a shortage of oxygen, it will cause the roots of the vegetables to rot.
It is possible to increase the amount of dissolved oxygen by lowering the temperature of the circulating water, but it is not very practical (in terms of electricity costs) to lower the water temperature using a cooling system.
In addition, the lack of oxygen could not be solved only by aeration with an air pump, so I would like to increase the amount of dissolved oxygen by using the property of absorbing oxygen from the water surface.

Dead water area occurred under the surface of the tank without a pump, and the water was stagnant.

This is a general view of the indoor hydroponics system at home.
From the water storage tank on the lower left, a pump raises water to the top PVC pipe, and after passing through the second and third PVC pipes, the water reaches the water storage tank and seedling tank on the lower right.
The difference in height between the right and left water storage tanks allows water to circulate through a single pumping pump.

This is a picture of the water storage tank only, but there is a pump at the bottom of the tank in the foreground, so the water in the tank circulates rather well.
The tank in the back does not have a pump, so only the surface of the accumulated water circulates, and the area surrounded by the blue frame is dead water.
A very small amount of water on the surface of the water may be able to absorb oxygen, but the dead water area below the surface, where water cannot circulate, cannot take in enough oxygen.
This area was used as a seedling growing space, but in order to solve the lack of oxygen caused by the rise in room temperature, we will modify the tank in the back.

Water pumped up from the dead water area is dropped to the surface and circulated.

The hose connected to the upper right (PVC pipe) is placed in the tank.
Although the water is not 100% circulating, the water in the area indicated in red tends to stagnate.
Only a small amount of water on the surface was flowing to the left tank, so we installed a pump in the right tank as well to improve the situation.

By installing a pump in the tank on the right, the stagnant water under the water surface was sucked up.
By bringing the sucked up water back to the surface of the water in the same tank, the surface of the water is made to ripple and the amount of oxygen absorbed is increased by increasing the surface area.
As the oxygen-deficient water is brought to the water surface, the amount of oxygen in the entire tank has increased.

In addition, we cut the hose extending from the PVC pipe so that it was above the water surface instead of in the water.
This should make the water surface ripple more violently and absorb oxygen more easily.
I can’t say for sure because I can’t buy a dissolved oxygen meter because it’s too expensive, so I can’t check the numbers.

In the video above, there is no lid on the water storage tank, but I usually put a lid on it because sunlight causes algae to form.
The water hose and the pump that circulates the water are both above the surface of the water, so there is a lot of noise, but I’m willing to turn a blind eye to it.
The lettuce leaves were almost shriveled at one point, but after switching to this method, they seem to be in better condition (maybe).
In the case of root rot caused by rising water temperature, making the water surface ripple may help.

Indoor Hydroponics: From Lettuce Seedling to Harvest with LED Auto-Lighting PVC Pipe Equipment

There are quite a few people who have been doing hydroponics using PVC pipes, and I am one of them.
I’ve been growing hydroponics using PVC pipes in a half-underground space, but due to the nature of the half-underground space, I can hardly use sunlight, and I’ve been relying on LED fluorescent lights to grow lettuce.
I decided that it would be a shame not to use the sunlight even though we have the sun, so I forced myself to create a space near the sunny window on the second floor by drastically decluttering things, and decided to make a second PVC pipe hydroponics system there.
Here is the record.
See the video below.

There are three power sources used: a pumping pump, an air pump, and a smart plug that connects to the LED lights.
The pump sends water up to the top PVC pipe, and the water is circulated by the pump and gravity, while the water tank at the bottom can be used to grow seedlings.

Creating the base floor

I don’t have any pictures for the article, so I’ll explain with the time code of the video attached.
0:00 Creating the base floor

Use wood to make a floor for the water tank.
I used a plastic wardrobe case that can be easily processed and is inexpensive, so I asked the home center to cut it so that it would be the width of the wardrobe case plus about 20 cm.
A single piece of companel is not strong enough, so I inserted 2×2 wood under the companel to reinforce it.
If the length of the board is longer than the length of the window, the vegetables planted at the edge will not be exposed to sunlight, so I made the length of the base as long as the window.
Since we were planning to use PVC pipe parts to branch the system and operate it in two rows, there would be a difference in the amount of sunlight between the row near the window and the row on the room side.
I installed casters on the base in case the difference was so great that I had to flip the PVC pipe system. So far, I haven’t used them much.

Making a frame to put the PVC pipe on.

0:37 Making a frame for PVC pipe

We will make a frame for installing three rows of PVC pipe equipment assembled in two rows.
However, if the PVC pipes are too close to each other, the vegetables will bump into the PVC pipes when they grow, so we decided to make three rows with room to spare.
The frame is made of two sets of 2x2s assembled in a “U” shape, turned 90 degrees, and the upper part is fixed with more 2x2s to prevent the frame from wobbling.

Fixing the frame to the floor using an angle

0:49 Fixing the floor and frame

Use the angle to fix the floor and the frame you made.
Normally, we can fix the floor by screwing from the back side of the floor, but when it comes time to dismantle the hydroponics equipment, we will have to turn the equipment itself over.
This time, I used angles to fix the floor and frame so that I can dismantle it smartly from above.

Processing the drainage hose for the water storage tank

1:21 Processing drainage hose for water storage tank

The drainage part of the water storage tank is made by combining a female drainage hose used in washing machines or under sinks and a male plumbing part of the same length.
The threaded part of the plumbing component is too long to fit into the drain hose (female), so I cut it off so that it fits perfectly after turning it in.
Because it is a small part, it is difficult to cut it with a saw while holding it down by hand.
I cut it while holding it in place with the vise I bought when I made the first hydroponic system before.
Also, if you have a lot of opportunities to cut PVC pipes (there are very few people who do), you can prepare a special pipe saw to cut PVC pipes very well.
You can also use a wood saw to cut the pipe, but it will not work because it will catch too much.
After cutting, use a hole saw to make a hole as small as or slightly smaller than the plumbing component.
Insert the plumbing parts into the holes and connect them to the drain hose.
Since this is the part where water flows directly, we caulked the inside and outside to prevent water leakage.

Cutting the PVC pipe

3:09 Cutting PVC pipe

Cut the PVC pipe according to the length of the window.
This time we needed a total of six PVC pipes in two rows and three tiers.
They are sold in lengths of 1m, 2m, 4m, etc. at home centers, but the longer the length, the lower the unit price, so if you want a large quantity, buy 4m and cut it yourself.
If you want a large quantity, you can buy 4 meters and cut it yourself. As I recall, 2 meters is 1300 yen, but 4 meters is like 1600 yen.
Using a vise and a pipe saw, I cut it to fit the width of the window.

Painting the floor, frame, and PVC pipe

3:38 Painting the frame

If you don’t think about preservative treatment, you don’t really need to paint it, but this time I wanted to make it a little cooler, so I painted the frame and floor dark brown.
I wanted to give it a foreign feel, so I decided to paint the PVC pipe white, and after a bit of research, I found out that the paint can be applied to PVC pipe as well.
After painting it and letting it dry for a day, I lightly scrubbed the surface of the PVC pipe with my fingernail and it peeled off, so I thought, “What is that information?
This is the reason why only the top PVC pipe device in the video is white in color.

Assembling the PVC pipe

4:13 Assembling the PVC pipe

Water enters through the spout, branches off to the left and right, passes through two rows of PVC pipes, and then merges again to be drained, and the drained water is poured into the spout of the second PVC pipe device.
Use branching parts and elbows to form a “L” shape.
I didn’t do it because my hidden theme was “dismantleable device”, but it would be better to use PVC pipe adhesive on the connection part or caulk it after the connection to prevent leakage.
In this design, we don’t use such bonded materials, but even if a leak occurs, the water storage tank underneath is designed to catch the leaked water.
Another advantage of not using glue is that the water level in the PVC pipe can be controlled.
The bifurcated parts are also used at the confluence, and the angle of the bifurcated parts at the confluence can be changed by turning them by hand, for example, upward to raise the water level or downward to lower it.
If the water level is too high, the roots will not get enough oxygen and root rot will occur, so I decided to assemble it in a way that does not require glue so that I can change the water level later.

Drilling holes in the PVC pipe

5:51 Drilling holes in PVC pipe

We will use the hole saw to make a hole in the PVC pipe for planting the seedlings we have grown.
The seedlings are grown in seedling pots in the water storage tank, and we want to plant the seedlings in the PVC pipe with the seedling pots, so let’s choose a blade that can make holes large enough to hold the seedling pots.
In order to avoid overlapping leaves, I spaced the holes about 15 cm apart for the middle-grown seedlings, and about 30 cm apart for the larger lettuce.
The top row had 20 holes in two rows of 10 holes each, and the middle and bottom rows of PVC pipes had 10 holes in two rows of 5 holes each.
If burrs appear on the cut edges of the holes (they always do), polish them with a file.
Shavings and scraps will accumulate inside the PVC pipe, so rinse the inside with water.

Installing the PVC pipe kit

6:48 Installing the PVC pipe kit
Place the assembled PVC pipe device on the frame you created.
Insert the upper drainage hose into the middle water inlet, the middle drainage hose into the lower water inlet, and the lower drainage hose into the water storage tank.

Installation of the pumping pump

7:24 Installation of pumping pump
We will install a pump to send water from the water storage tank to the upper PVC pipe.
To prevent the formation of algae, the hose to be attached to the pump is not a transparent one, but an “algae-proof” one.
Also, as for this device, the height will be about 180 cm.
When buying a pumping pump, be careful to choose a product whose maximum pumping distance exceeds the height of the device, or you will not be able to send water upward.
After attaching the algae-proof hose to the pump, extend the hose to the water inlet of the topmost hydroponics equipment and plug it in.

Processing the surface of the water storage tank

8:16 Processing the water storage tank
I use a plastic transparent case as a substitute for the water storage tank, but if I use it as it is, the sunlight will directly irradiate the water inside the case, and algae will form just like the hose.
In order to block out the sunlight, I used an aluminum sheet (leisure sheet? To block out the sunlight, use an aluminum sheet (leisure sheet? heat insulation sheet?) and double-sided tape. and double-sided tape.

Processing Styrofoam for seedlings

8:38 Processing Styrofoam for seedlings
We grow seedlings in a water storage tank, but if the height of the support for the seedling pot is fixed, when the water level drops as the water decreases, the roots may not be able to reach the water and the seedlings may die if they notice.
By making a hole in the styrofoam large enough to hold the seedling pot, setting the seedling pot, and floating the styrofoam in the water tank, even if the water level drops, the styrofoam will drop with the water level.
Measure the length of the bottom of the wardrobe and cut out a piece of styrofoam a little smaller than that.
The Styrofoam used in the video is Styrofoam.
If you use Styrofoam, the cut surface will be ragged and it will not look good.
I wondered if I should use a pen-type styrofoam cutter, but I was reluctant to use a styrofoam cutter to make 60 holes, so I changed to styrofoam.

Pouring in water with liquid fertilizer

9:26 Pouring in water with liquid fertilizer
Now that most of the preparations are in place, I start adding water with liquid fertilizer to the water storage tank.
I use the liquid fertilizer from the old Otsuka House, and adjust the EC value to be around 1.3.
Once the water tank is full, I turn on the pump to send water to the upper PVC pipe system, and when the water in the tank runs out, I turn off the pump and fill up the tank again.

Start water circulation

9:46 Water circulation begins
As you repeat the process, the inside of the upper PVC pipe device will fill with water, and the drained water will go to the middle device, and when the middle device is filled, the water will go to the lower device, and when the lower device is also full, the water will come back to the storage tank.
Keep adding water until the water is able to circulate.

Set the styrofoam and seedlings.

10:28 Set the styrofoam and seedlings
Set the seedlings in the styrofoam that we cut out and poked holes in earlier.
Since we had already grown sponge seedlings by planting germinated seeds in the sponge, we inserted the sponge seedlings into the seedling pots and inserted the pots into the holes in the Styrofoam.
The seedlings are then inserted into the holes in the Styrofoam.

Installing LED lights

11:47 LED light installation
In order to grow lettuce with sunlight, we built a hydroponic system near the window, but it is still difficult to get enough light indoors depending on the angle of sunlight and time of day.
In order to compensate for the lack of sunlight (although we will also use sunlight), we will install LED fluorescent lamps.
I thought it would be convenient to have something that doesn’t need a light fixture and emits light just by plugging it into an outlet, so I connected them with a connecting cord and used them.
I used cheap LED fluorescent lamps that cost about 1000 yen each, but they work fine.
The electricity bill is about 300 yen per lamp after 24 hours of continuous illumination for a month.

Setting the lighting time of the smart plug

12:13 Setting the lighting time for the smart plug
We can get a good amount of sunlight in the morning and evening, but during the rest of the day, we would like to use LED lighting.
It’s a hassle to manually turn on and off the lights every time, so we made it so that the lights can be turned on and off automatically when the set time comes via smart plug.
A timer type light can be used instead, but even during the daytime, for example, when it is cloudy and there is not enough sunlight, the lights can be turned on manually from the app.

Experiment with turning on the lights automatically

12:48 Experiment of automatic lighting
I experimented to see if the lights would actually turn on at the specified time.
I set the lights to turn on at 4:30 in the evening, and they turned on successfully, although there was a time lag of about 5 seconds.
I set the lights to turn off at 5:00 in the morning, and I haven’t been able to check the timing of the lights turning off (since I’m still sleeping at that time), but when I woke up in the morning and looked at the LEDs, they were gone, so I don’t think there is a problem here either.

Things I failed to do but have improved

Since warm air rises upward, there is quite a difference in room temperature between the half-basement space and the second floor space.
I didn’t know that the higher the room temperature, the higher the water temperature, and the higher the water temperature, the harder it is for oxygen to dissolve into the water.
After a day or two of planting the seedlings in the hydroponic system on the second floor, the lettuce gradually lost its vigor and began to show symptoms of root rot.
Since we were only running one air pump in the small tank, it seemed that we were running out of oxygen.
First, I changed the air pump to a high-powered one.
In addition, I turned the parts in the drainage section to slightly lower the water level in the PVC pipe so that the roots could be directly exposed to air.
After cutting off the rotten roots, I planted the plant again and a few days later, I could see new white healthy looking roots growing out of the sponge.


[mac Big Sur]If you want to record sound from your PC, use BlackHole.

I tried to install Soundflower on my PC (OS: Big Sur) to record the sound coming out of my M1 model macbook, but
I tried to install Soundflower on my PC (OS: Big Sur) to record the sound coming out of my M1 model mac, but I got a message that “Soundflower.pkg” cannot be opened because the developer has not been confirmed.
After some research on Google, I found that
After some Googling, I found out that the solution is to go to [Settings] -> [Security & Privacy], allow downloads, and click [Open As].
I’m sure everyone (including me) has found a solution like this.

I’m not sure if you’ve tried to install Soundflower on your macbook.

If you can’t, you can’t, so install BlackHole instead of Soundflower.

Steps to install BlackHole as a replacement for Soundflower

First, proceed to the official website.

BlackHole official website
From the top, enter [email address], [first name], and [last name], then click [Subscribe for Free Mac Download].

If your email address is entered correctly, you will soon receive an email from BlackHole with a download link, so click on the download link.

Open the link in the email to open the BlackHole download page, and click on the “BlackHole 16ch v0.2.9” to start downloading.

Click on the downloaded pkg file to open the installation window, and follow the steps in the installer to install the software.
After the installation is complete, you will be asked if you want to put the installer in the trash, but you don’t need it anymore, so throw it away.

Where is it? To open the installed BlackHole

I tried to start up the installed BlackHole, but I couldn’t find it when I looked into [Applications].
The name of the application is “Audio MIDI Settings”.
If you want to open it from the Dock application, go to [Applications] -> [Launchpad] -> [Other] -> [Audio MIDI Settings].
If you want to open it from Finder, you can go to [Finder] -> [Applications] -> [Utilities] -> [Audio MIDI Settings].

How to set up BlackHole to record sound from your macbook

Now that it is installed, let’s configure it.

When you open Audio MIDI Settings, a window like the one above will open. Click the [+] mark in the lower left corner and select [Create Multiple Output Devices].

Check the “BlackHole 16ch” checkbox.

Right-click on the [Multiple Output Devices] you just created to open the window shown above, and click [Use this sound output device].
You can now close the Audio MIDI Settings window.

Set the microphone to BlackHole in QuickTime Player.

Right-click on QuickTime Player and open [New Audio Recording].

Click on the red record button to the right to select the microphone you want to use.

If you can’t record, please reboot after installation.

Try playing sound from your MacBook on Youtube, itunes, or anything else.
If the volume gauge of the QuickTime audio recording swings, you have succeeded.
If not, you may need to restart your computer.
Restarting the computer may help if the recording doesn’t work right after installing BlackHole or after changing Audio MIDI settings.
If the volume gauge is not moving, even if you can click the record button, no sound will be recorded.

When using BlackHole, you cannot use the function keys to adjust the volume.

When the microphone is set to [BlackHole 16ch], you will not be able to adjust the volume or mute the microphone using the function keys.

If you want to adjust the volume using the keyboard such as [F10], [F11], [F12], etc., such as when you want to check the recorded audio file, please go to [System Preferences] -> [Sound] and change it back to the built-in speaker of your macbook.

What to do if you hear a blurry sound when you play back a recorded audio file?

This is a little off topic, but for example, when using Google Translate on your computer, you can only select a female voice, but if you want to have it read out loud in a male voice, you can use Siri instead.
How to use Siri to read out a sentence in a male voice
You can also use BlackHole to save the voice as an audio file, which you can then use to create a narration for Youtube.
End of story
When you successfully record and play back the audio file, you may find that the sound is blurred, or as if it was recorded in a large room.
I don’t know how to describe it, but it’s not exactly howling.

If you feel the above indescribable discomfort when you play the resulting audio file, try changing the recording quality of the audio recording in QuickTime Player from [High] to [Highest].
I tried various things in the Audio MIDI settings under [Speaker Configuration], but no matter what I did, it didn’t improve, but just changing it to [Highest] usually did.

Summary of using BlackHole with Big Sur

I used BlackHole to record the sound of my PC with the result that I could not install Soundflower with Big Sur.
I had to reboot to get it to work (or was that just me?). But I was able to record without any problems.
I’m sure many people are in the process of switching to a macbook with M1 chip, so I hope this will be useful for those who have no choice but to switch to BlackHole.








Hydroponics: Experimenting with how the duration of light exposure affects the growth of lettuce.

Using an entire wall indoors, we will try our hand at hydroponics using PVC pipes.

I used light bulbs to germinate leaf lettuce by continuously shining light on them in three patterns: 0h, 12h, and 24h, to see what kind of difference the light exposure time makes.
It seems to be a photophilic plant, so I guess I can understand the results to some extent without actually doing it, but I’ll give it a try.
The lettuce in the middle of the photo above has grown so well that it is now tall enough to hit the light in the shading device, so I moved it to the hydroponics unit.
If you want to watch the video, please click the link below.

Here you go.

Moisten the container with a sponge and sow lettuce seeds.

Prepare a suitable container (in this case, a cut plastic cup) and cut a sponge to fit the container.
Moisten the sponge with water and sow the lettuce seeds on it.
There is also a method of covering the sponge with toilet paper to prevent it from drying out, but it was too much trouble, so this time I sprayed water on it with a mist sprayer.

Shading with PVC pipes and controlling the lighting on/off with a smart plug

Shade the seeds.
The 0h seeds will not be exposed to any light, so we will cover them with aluminum foil and leave them there.
The 24-hour seeds will be exposed to light all the time, so I hung a light bulb

inside a PVC pipe and covered it with aluminum foil.

The 12h seed will be lighted for 12 hours, shaded for 12 hours, and then repeated.
You can turn the bulbs on and off manually, but since I had an extra smart plug, I automated the lighting on and off.
It was a smart plug from a company called Meross, so I installed a special app and the lights turn on at 16:00 and off at 4:00 in the morning, repeated daily.

Lettuce growth rate one week after sowing

It has been two days since seeding, and none of the 0h lettuce, 12h lettuce, or 24h lettuce has germinated.

I forgot to observe it on the third day, and now it’s the fourth day.
It’s a bit scrawny. Super scrawny.
This one might not make it.

This is a 12-hour light-irradiated lettuce, and it germinated without any signs of overgrowth.
I just put the seeds on it, but the germination rate is good and it looks a little small.

Here are the lettuce seeds that were left under the light for 24 hours.
They germinated, but they seem to be a little smaller than the 12-hour lettuce.
Considering the time it takes to germinate, 12 hours of light and 12 hours of shading seems to be a good idea.

It’s been six days. The lettuce, which is shaded all the time, is no longer good.

The lettuce has been shaded for 12 hours with a 12-hour light, but many leaves have come out.

This is the lettuce that has been exposed to the light for 24 hours.
Compared to the lettuce that was exposed to the light for 12 hours, each leaf is larger and the leaves seem to be more spread out.
I wonder if this is because they absorb more light.

One week has passed.
As for the 0h lettuce, there is nothing more I can do to save it, so I will end my observation.
As for the 12h lettuce, the leaves themselves are getting bigger, but the opening seems to be weak.
It looks like it is growing upwards.

This is the 24h lettuce a week later, and the leaves have opened up nicely, and the main leaf (or is it called that?) is growing out from the middle. It looks like it is growing the best.
It looks like it is growing the best.

How much lettuce has grown in the last 10 to 18 days

This is the 12h lettuce, which is now on its 10th day.

This is the 24h lettuce.
The leaves seem to be more vigorous than those of the 12h lettuce, and the main leaves (I wonder if they’re called that?) are bigger. I wonder if 24 hours of continuous light is the right way to go.
I wonder if it’s right to expose them to light for 24 hours straight…

This is the 24h lettuce.
The leaves seem to be more vigorous than those of the 12h lettuce, and the main leaves (I wonder if they’re called that?) are bigger. I wonder if 24 hours of continuous light is the right way to go.
I wonder if it’s right to expose them to light for 24 hours straight…

This is a 24-hour light-irradiated lettuce, and the color of the leaves is starting to look like sunny lettuce.

This is the 12h lettuce on day 18.
I thought, “Maybe this is the one that needs to be thinned out in the middle? But it was already too late.
The result might have been different if I had thinned it out when it was in the twin-leaf stage. Let’s go back in time.

This is a 24h lettuce.
The main leaves are growing in earnest and getting bigger, and I noticed that they were almost touching the hanging lights.
If I don’t think about thinning (which I should), it seems that the sunny lettuce will grow faster if it is exposed to light 24 hours a day.
I’d like to end the experiment on the 18th day, as it looks like it’s not good for the lettuce to be exposed to the light directly.

Replanting the grown lettuce plants into the hydroponic system


The grown lettuce plants were transferred to the hydroponics unit.
I took the lettuce and sponge out of the cup and gently loosened the roots growing from under the sponge so as not to cut them.
Inside the processed PVC pipe (gray pipe), water with liquid fertilizer and oxygen is circulating.
After loosening the roots until they are long enough to soak in the water, I set the lettuce in the PVC pipe.
We have installed LED lights near the lettuce plants, so they will continue to be exposed to light 24 hours a day, but will they ever be harvested?
In other words, if it harvests well, there will be a follow-up report, if it dies, there will be no follow-up report.

How to make your own water level sensor for hydroponics. Getting ready for automatic water supply using solenoid valves.

We are going to try hydroponics using PVC pipes on one wall of the room.
The water is stored in a water tank and circulated through the PVC pipe by a pump, but as the vegetables grow and evaporate naturally, the amount of water in the tank diminishes (I haven’t reached that point yet, but…).
(I haven’t reached that level yet, but…) To prevent moss growth, the water tank is covered with a light-shielding aluminum sheet, so you can’t see the amount of water in the tank at a glance.
In such a case, it would be nice if there was a system to automatically supply water as the water level decreases.

A water level sensor is necessary for the automatic water supply system you dream of.
You don’t need it yet! If you say, “You don’t need it yet!” that’s as far as I’ll go, but since I’m going to go out of my way, I decided to make one myself.
The materials needed to make the sensor are quite expensive, but each part is pretty cheap, so I think you can make it yourself at a reasonable price.
To watch the video, click on the link below.

Here you go.

Prepare the parts necessary for making your own water level sensor.

First, let’s prepare the materials.
Water level sensor module

KK moon 9V-12V AC/DC センサモジュール 水コントロールモジュール 水位検知センサー 排水ポンプ水コントロールモジュール 液体レベルコントローラー
There seem to be many types of water level sensor modules, but I bought this one because I felt like I could use any of them.
Electrician’s Pliers
These are used for stripping plastic cords and wires, and for snapping terminals on copper wires.
If you’re doing electronics work, it’s a good idea to have one.
I bought mine at Home Depot, and they are the same electric pliers as in the link.
AC adapter and DC jack cable
This product itself is very cheap, but it takes a long time to arrive, probably because it is shipped directly from China or something.
You might want to buy a few extra so you can use them when you get the urge to make your own.
Various other things
There are many other things you can do, but you should be able to find most of them at a home improvement store.
You can buy male plugs, female plugs, bar terminals, ring terminals, insulation caps, vinyl cord, wire, bolts and nuts, etc., depending on what you want to make.

Process the vinyl cord so that it forms a T-shape.

The white female plug on the left of the picture is connected to the device you want to turn on and off depending on the water level, and the white male plug on the right is connected to the outlet.
Let’s modify it so that it looks like this.

Split the vinyl cord.

Cut the vinyl cord to the appropriate length and split it to the left and right.
Make a “split and united” cord that is about the same length as the cord stretched to the left and right.

Peel off the vinyl cord sheathing.

We will use electric pliers to strip the cord insulation.
Strip the cord in six places: two on the left, two on the right, and two on the bottom.
It can be done with scissors or cutters, but it’s a pain.

Clamp the ring terminal to the copper wire that came out after peeling.

Peel off the coating to reveal the copper wire.
Insert the copper wire into the ring terminal and tighten it with electric pliers.
The ring terminals are just for easy connection to the male and female plugs on the left and right sides, and you don’t need them to twist the copper wire.

Screwing the ring terminal to the plug

Put the plug screw in the hole of the ring terminal and tighten it as you go.
Connect both the left and right plugs and put the lid back on.

Attach the bar terminal to the water level sensor connection.

Slightly split the vinyl cord on the bottom side to make a two-way connector.
As with the ring terminals, put a stick terminal on each copper wire and put an insulating cap on the terminals to prevent them from touching each other.
If the copper wire is stranded (a bunch of thin copper wires), it is likely to come loose when connected to the water level sensor, so I decided to use a bar-shaped terminal this time.

Connecting the processed vinyl cord to the water level sensor

Connect the vinyl cord to which you just connected the stick terminal to the number 2 and 3 of the water level sensor.
The screws are small, so I used a precision screwdriver to tighten them.
I wonder if there is such a thing as which one to plug into which.
In my case, I plugged the cord extending from the male plug side into number 2 and the cord from the female plug into number 3, and it worked fine.

Connecting the colored wires to the water level sensor

Attach the wire sensor, which measures the water level by placing it directly into the water, to the blue part on the other side of the vinyl cord.
For each color, all you have to do is strip off the coating of the part to be connected, and attach the stick terminal and insulation cap, so the work is the same as for the cord.
In the picture above, the black wire indicates the lowest water level, the red wire is the highest water level, and the yellow wire is the junction to start feeding power to the device or not.

Connect the AC adapter to the DC jack cable and connect it to the water level sensor.

Attach a stick terminal and an insulating cap to the end of the DC jack cable as shown in the photo above so that it can be connected to the water level sensor.

Plug the DC jack cable into the photo area.
The water level sensor itself will be powered by this AC adapter.

I drilled holes in the plastic case to fix the main unit.
I also drilled holes in the side of the case and threaded the various cables through.
I’m sure I’m explaining how I fixed it quickly, but this was the hardest part of the whole process…

Creating the sensor part, connecting the devices and checking the operation.

Create the sensor part that is actually put into the water.
The part that senses the lowest water level is the longest straw, the junction where the power supply starts is in the middle, and the line that stops the power supply is the shortest straw part.
Pass each wire through the mouth of the straw and leave the tip of the stripped wire sticking out from the end of the straw.
Now let’s check the operation.
Plug the AC adapter, which is the power source for the water level sensor, and the male plug of the vinyl cord into the outlet.
Connect the female plug of the vinyl cord to the male plug of the device you want to move depending on the water level.

Let’s put the wire sensor into the water.
It is a little difficult to see in the picture, but the black and yellow wires are submerged in the water.
The tip of the yellow wire in the middle, which is the branch point, is submerged in water (indicating that the water level is not decreasing), so the rear light is not being powered.

I lifted the sensor by hand.
The sensor is usually fixed in place, but since this was an energized experiment, I didn’t mind.
I lifted up the sensor by hand, that is, I intentionally made the water level low, but as soon as the yellow wire, which is the junction point, came out of the water, the power started to flow and the light came on.
As soon as the yellow wire, which is the junction point, came out of the water, the power was turned on and the light came on. When the yellow wire was submerged again in this state, the power remained on.
When the red wire, which detects the highest water level (overflow prevention), is submerged, the power stops.
The plan for the future is to connect the male plug of the solenoid valve connected to the water supply to the female plug of the vinyl cord, and sink the wire sensor into the water tank.
The end of the hose of the solenoid valve is inside the water storage tank, and when the water level in the tank drops below the middle of the wire sensor, the solenoid valve will open and water will be supplied automatically.
The water level in the tank rises as the water is supplied, and when it reaches the top sensor, the water supply is stopped… It’s very dreamy.
At this point, the water level sensor has not been used yet, and I feel like I’m getting ahead of myself, but I’m happy to say that I succeeded.

[Hydroponics] Lettuce has root rot! Trying to revive it & urgent environmental improvement

I was growing lettuce and small tomatoes outdoors in a hydroponic system made of PVC pipes.
After a few days of moving the whole system indoors, the vegetables seemed to be somewhat listless.

I had a bad feeling, so I checked the roots and found that it had root rot.
It looked like kelp in miso soup.
I heard that once a plant has root rot, you can’t get it back, but I thought I could cut off the rotten part and revive it by using a method like cuttings.
I would also like to solve the problems caused by moving the plant indoors, such as lack of sunlight, lack of oxygen in the water, and the development of water moss.
To watch the video, click on the link below.

Here you go.

Cutting the roots of rotten lettuce and small tomatoes with scissors

I started to cut the rotten part of the lettuce with scissors.
In the photo above, I was too scared to cut the rotten root, but I heard that there is no possibility of curing root rot, so I cut the entire rotten part.

The roots of the small tomatoes weren’t as bad as the lettuce, but they did look rotten in places.
I cut off the suspicious parts with scissors.

I wrapped the cut lettuce in a sponge to keep it from falling over and set it in a bucket so that the cut ends and stems were immersed in water with liquid fertilizer.
Hopefully, new roots will grow…
As for the lettuce, I’ll give it a few days to see how it does.
I cut off the rotten roots of the tomatoes and put them back in the multi-stage hydroponic system made of PVC pipes in the room.
I’ll keep an eye on them for a few days.

The roots of the lettuce did not recover, and I gave up on the small tomatoes.

It was a disappointing result.
As for the lettuce, five or six short and thin roots grew from the part that was soaked in water, but the growth of the roots was slow, so the lettuce itself wilted due to the lack of water.
The mini-tomatoes were grown in a multi-stage system, but upon closer examination, since we were circulating water and growing other vegetables at the same time, the rotten roots might have an adverse effect on the entire water supply.
In order to avoid the total destruction of the vegetables, we also removed the small tomatoes.
As a result, it was tough to revive the roots of the vegetables that had suffered from root rot at this stage…unfortunately.

Environmental improvement #1: Supplying oxygen to the water with an air pump

Someone somewhere told me that circulating water makes the water move, which in turn makes it easier for oxygen to reach the water.
I was relieved by that, but it resulted in the root rot that happened.
So I would like to use an air pump for the aquarium, air tubes, and air stones to force oxygen into the tank.
I chose one that looks a little stronger than the others because I expect the water volume to increase with the increase of PVC pipes in the future.


All you have to do is connect the air pump, air tube, and air stone, put the stone in the tank, and plug it in.
The water should now be highly oxygenated.

Environmental improvement #2: Install LED lighting to eliminate the lack of sunlight

I installed one LED light about a meter long on the ceiling.

It is simple to use, just plug it into a household outlet.
After I moved the hydroponics equipment indoors, I was only using soft indoor lighting, so I think the light quantity was not enough.
To be honest, it seems that one LED light is not enough, so I plan to purchase more in the future.

Environmental improvement #3: Covering the water storage tank with a leisure sheet to prevent moss growth

I covered the water storage tank with a light-shielding leisure sheet because I heard that direct light on the circulating water causes moss to form.
I think it would be better to shade the holes in the PVC pipes that don’t have seedlings on them yet, as well as the water supply hose connected to the pumping pump, but I haven’t recovered from the shock of the root rot yet, so I’d like to do it sometime (sometime)

I modified part of the lid of the water storage tank to allow me to run the drain hose, water supply hose, air tube, and power supply.

The top photo is a pipe saw (saw) for PVC pipes, and the bottom is a saw for woodworking.


Growing small tomatoes, all-purpose leeks, basil, and strawberries in an improved hydroponic system

I was not able to revive the lettuce and small tomatoes with root rot.
I don’t know at this stage what was the worst, but in the improved environment, I have been growing mini-tomatoes from cuttings, all-purpose green onions that I bought from the supermarket and left only the roots, basil and strawberries that I got from Home Depot.
The seedlings from Home Depot are sold in pots with soil, so I wash off the soil outside, leave the roots alone, and grow them in PVC tubes.
Water is essential for hydroponics, but we didn’t have a sprinkler (outdoor water supply) at home, so I had a friend lay one for me at a reasonable price.

There are a lot of incidents that can happen.
I feel the greatness of my predecessors who are successfully doing hydroponics.
I would like to study them so that I can be as close as possible to their success.
The lettuce has gone root rot, so the salad has disappeared from our table…

[Hydroponics] Moving the outdoor PVC pipe system indoors and getting it working again.

Using an entire wall of the room, we will try hydroponics using PVC pipes.
The PVC pipe with holes for planting seedlings was not operational in the summer of 2020, but now it is operational and lettuce is growing like crazy.

Preparing to dump the circulating water and bring the equipment into the room.

I would like to move the hydroponics equipment that was experimentally set up outdoors indoors and practice indoor hydroponics in earnest.
The structure of the cultivation system is a PVC pipe, a washing drainage hose, a water storage tank (substituted with a cooler box), a pump, a 12mm inner diameter water hose, a stand (container), a sponge, and seedlings.
The PVC pipe is wrapped with a silver leisure sheet to prevent the water temperature in the pipe from rising too high.
However, in reality, the circulating water temperature was over 30 degrees Celsius when it was set up outdoors in the middle of summer, so it might be better to wrap the leisure sheet than not to wrap it.
After dumping all the water in the PVC pipe and the water storage tank, we were ready to start moving.
To watch the video, click on the link below.

Here you go.

Setting up the unit, PVC pipe, and water tank in the room

Line up the unit, PVC pipe, and water tank in the same way as for the outdoor unit.
We want the water to drain automatically when it reaches a certain level, so we need to place the water tank below the PVC pipe.
Keep the end of the hose inside the tank so that the water that drains from the hose returns to the tank.

Set the small tomato and lettuce seedlings in the PVC pipe.

After setting up the stand, PVC pipe, and water tank, the next step is to set the seedlings in the holes that we cut out.
It’s hard to tell from the picture, but the roots of this lettuce are about 30 cm long.
The roots themselves are white and beautiful because they are grown without soil, only water.
If you put the lettuce in the hole as it is, it will wobble and fall down, so wrap a sponge around the stem to make it a little bigger than the hole, and then insert it to hold it in place.
If you are using seedlings in pots with soil, which you can often find at home centers, fill a bucket with water and wash the soil gently.
When all the soil has been washed, wrap it in a sponge and insert it into the hole in the PVC pipe.

Install a pumping pump in the water storage tank.

Install a pumping pump in the installed water storage tank.
Without it, you can’t start anything.

Connect a hose with an inner diameter of 12mm to the water supply side, and put the hose into the inlet of the PVC pipe.
The size of the hose is perfect, and I’m sure I’m not the only one who gets frustrated every time when connecting it…
There is a suction cup on the bottom of the pump body, so you can fix the pump by simply pressing it against a flat surface inside the water storage tank.

Making water with liquid fertilizer to achieve an EC value of 1.3

I’ve dumped the water in the PVC pipe and the water storage tank outside because it gets very heavy when moving it, so I’ll make water with liquid fertilizer again.
The reason why I set the EC value (like liquid fertilizer concentration) to 1.3 μs/cm (microsiemens) is just because many people do so.
I’ve heard that it’s better to change the concentration according to the growth of the vegetables, but for now, I’ll stick with the EC value of 1.3…
The above article explains how to make concentrated liquid fertilizer for the OAT (formerly Otsuka) house.
Adding 50cc each of No. 1 and No. 2 concentrated liquid fertilizer to 10L of water will produce water with an EC of 1.3.
Depending on the capacity of your water storage tank, you can make water with liquid fertilizer several times.
In my case, I made 40 liters of water 4 times in total and put it in the water storage tank.

Turn on the pump to circulate the water.

Let’s quickly turn on the pump.
Water will be sent from the pump submerged in the water storage tank.
When the water level reaches a certain level, it will be discharged from the drainage hose.
The drained water comes back to the storage tank and is pumped again.
All you have to do is to add water with liquid fertilizer again while monitoring the EC value as the roots of the vegetables absorb water and the overall water volume of the hydroponics system decreases.
The hydroponics system has now been moved.
I just moved the one that was able to operate normally outdoors to indoors, so I don’t have any problems with it.
The mini-tomatoes haven’t turned red yet (there are green fruits), but as for the sunny lettuce and leaf lettuce, they grew quite well in the outdoor cultivation.
I was able to tear them off and serve them on the table every day, which greatly increased my chances of eating lettuce.
Now that we have moved the equipment indoors, the lack of sunlight is going to become a problem.
I wonder how much I can grow using LED fluorescent lights, …

I haven’t received the product yet, but I’m looking forward to it no matter what.
So long.

[Hydroponics] How to make OAT (formerly Otsuka) house concentrated liquid fertilizer and what to do when the EC value doesn’t match.

We are going to try hydroponics using PVC pipes on one wall of the room.
We have already made a frame for the PVC pipe and processed the PVC pipe.
We will grow crops by circulating water in the PVC pipe, but since we will not use soil, the crops will become undernourished if it is just water.
Therefore, I would like to make concentrated liquid fertilizer with OAT (former Otsuka) House’s concentrated liquid fertilizer and add it to the water for fertilization.
To watch the video, click on the link below.

Here you go.

Weighing OAT (former Otsuka House) No. 1 and No. 2 to make concentrated liquid

Weigh the two types of fertilizers from Otsuka House.
There seems to be a liquid fertilizer that is already made called Hyponica, but it seems a bit expensive, so I chose Otsuka House this time.

This time, we will finally make a concentrated liquid in a 2L plastic bottle container, but we will have to mix it in the middle of the process.
If we make 2 liters in a 2 liter PET bottle, it will be difficult to mix, so this time we use half the amount to make 1 liter of concentrated liquid.
Use an electronic scale to measure 150g of Otsuka House No. 1 and 100g of Otsuka House No. 2.
Put the fertilizer into a plastic bottle filled with 1 L of tap water using a wax tube.
You don’t have to use a wax tube or a ladle, anything is fine as long as you can put fertilizer.
When you have finished filling both No. 1 and No. 2 bottles, put the lids on and shake them around so that the water and fertilizer mix well.
No. 1 is smooth and easy to put in, but No. 2 is kind of (sticky?). But No. 2 is kind of (sticky?) like white sugar and hard to put in.
If it’s hard to put in, use disposable chopsticks, a stick, or anything else to push it in.
The resulting concentrated liquid fertilizer is yellowish in No. 1 and transparent in No. 2.

The difference between 200x and 500x concentrated liquid fertilizer

This article explains how to make a concentrated solution for use by diluting it 200 times, but the OAT (formerly Otsuka) house fertilizer manual describes how to make a concentrated solution for use by diluting it 500 times.
For example, if you want to achieve an EC value of 1.3 μs/cm (microsiemens), you will need 50 cc each of No. 1 and No. 2 for a 200-fold dilution and 20 cc each for a 500-fold dilution for 10 L of water.
Either way, the result will be the same, but between measuring 50cc and 20cc, the smaller amount should be harder to measure.
If you mistakenly add 60cc when you need 50cc, you will only get 1.2 times more, but if you mistakenly add 30cc when you need 20cc, you will have added 1.5 times more.
To make it easier to measure the amount of liquid fertilizer for 10 liters of water, we decided to use 200x.

Putting concentrated liquid fertilizer into water

Now, let’s quickly add the concentrated solution we made to the water.
I bought a 10-liter bucket at a 100-yen store to make it easier to see the amount of water.
I don’t know if the bucket will be full when it reaches 10 liters, or if it will reach 10 liters just before the bucket is full, but we’ll keep adding water.
I used an EC meter to measure the EC value of the tap water, and it was 0.146 μs/cm.
If you don’t have an EC meter, you can buy one for about 1,000 yen.

If you don’t have one, buy one at this time.
Measure 50 cc of each of the Otsuka House No. 1 and No. 2 concentrates, add them to the water, and mix them together.
Now you have about 10 liters of water with an EC value of 1.3 μs/cm, in which the liquid fertilizer has dissolved…
But when I actually measured it with the EC meter, it was 2.164 μs/cm, which is less than twice the concentration…
I don’t understand why at all.
I don’t know if it’s the water temperature or the EC meter, but I don’t know why there is such a big difference.
There was a possibility of spillage if I filled the bucket to the brim, so I added water to the very edge of the bucket and measured the EC again, and it dropped to 1.9, but it was still 1.9.
I decided to trust the EC meter this time, and I’d like to solve the problem by bringing the result of 2.164 μs/cm closer to 1.3 μs/cm.

How many liters of water do I need to add to dilute the water to get closer to the target EC value?

I thought I made it exactly right, but somehow the EC value is far from the desired value, just like me.
I know that I should add water to dilute it, but adding water and measuring it, adding water and measuring it, is not the way to go.
But as the amount of water increases to 30L or 50L, it becomes more and more difficult to know how much water to add to dilute the water, doesn’t it?
You can find out the amount of water to add by a simple calculation.
[Current EC value] ÷ [Target EC value] × [Water volume] – [Water volume] ≒ [Required water volume
The above calculation will give you the approximate amount of water you need to add.
The EC value of a bucket of water just barely containing 10 liters of liquid fertilizer was in the 1.9 range, so if we apply the above calculation, we get…
1.9 ÷ 1.3 × 10 – 10 ≒ 4.6
This means that if we add 4.6 liters of water, we should get an EC of 1.3.
I actually added water and measured again, and the EC was 1.21, which seems to be close enough.
Even if the current EC value, the target EC value, or the amount of water changes, I think you can use it by substituting each term.
However, it seems that the appropriate EC value for dilution or fertilization depends on the type of plant and its growth process (I haven’t reached that point yet, and I don’t have any knowledge at all…) The pioneers who have a lot of knowledge and experience are amazing.
I can’t wait to become one.

How much water will be in the PVC pipe?

Now that I have finally reached the point where I can make the concentrated solution and dilute it, it’s time to start circulating water in the processed PVC pipe.
The PVC pipe I bought is called VU100, which is about 10 cm in diameter.
The PVC pipe I bought is about 10 cm in diameter, called VU100, and it is cut into 300 cm pieces, so when it is full, 23 liters of water will enter the PVC pipe.
We have modified the end cap to drain the water when the water level reaches half, so the actual amount of water flowing through the pipe is about 11.5 liters.
We currently have four of these PVC pipes in operation (the remaining one is not in use yet).
Including the water in the storage tank, about 50 liters of water should be circulated by the pump and gravity.
I’ll write about it as soon as it’s ready.
Have a wonderful hydroponic life!