[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.

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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.

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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!