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.