Automate hydroponics NFT system

Hey all,

I’m currently in the process of building my own hydroponic NFT system. Sustainability is very high on my agenda and I want to use as little water as possible. Hence, I want to re circle the water in my NFT system and only drain the entire system when the crops are fully grown and ready for harvest. However, re circling the water does not get rid of the plant waste and hence, my EC values keep rising and rising.

For automation I want to use a pump that adds nutrients when the EC values are below a certain threshold, however with rising EC values this is a problem. Is it possible to even automate a re circling NFT system? If so, how?

Currently, I have a ceramic filter in the system.

It’s possible but not easy to achieve. You need pure engineering to develop a chip that measure the EC and alert and regulate automatically. There are in the web some open source projects that show you how to build an Conductivity Meter. You need Electronics and Software Development. Finally I can add that for NFT I concluded that it’s better to check 1 or 2 times a week to regulate the EC than build a complex EC full automated. In my experience the Automatization only have meaning when the value of the application matters. There a things that you don’t need to automatized. You need to answer if it’s really important the Automatization or not depending the application.

I agree with Erme and would add that a rising EC would indicate the nutrient is too strong for the current growth stage and/or environmental conditions. Running a crop from transplant to harvest on the same reservoir will depend a lot on the crop type and how long it takes to grow, for example, lettuce would be somewhat easier than tomato. Maintaining the EC of a recirculating reservoir doesnt guarantee it will be balanced from an elemental point of view. If the crop removes predominently nitrate and you add nutrient to maintain EC,you are not only adding N but also P,K,Mg, and a host of micronutrients which can lead to issues that compromise plant health and, in turn, yield…

Thanks for your quick reply!

The problem I am facing however is that without even adding nutrients, the EC values keep on rising. This makes it difficult to even maintain the EC, I don’t know what causes this rise in EC. My expectations would be that over time the EC values would drop because the lettuce plants would absorb nutrients and hence the EC value would drop.

If the plants are taking up more water than nutrient, the EC in the reservoir will rise. If the water level in the reservoir is dropping and the EC is rising you should reduce the nutrient strength (add ro water) until you begin to see a drop in the reservoir EC .
It would help if you could provide some details such as current res EC, volume of res and how much is being used per day/week etc.

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Yes Atom I Agree… i think the rising EC it’s very probably caused by the water absorption.

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So, correct me if I am wrong here, when the amount of water remains constant there will be a drop in EC values. Hypothetically, let’s say my EC values are 2 and because of water absorption my EC has increased to 3. After adding water to the initial height, would my EC values than drop below 2?

If the grow is indoors under lights it wont take long to find the correct level. If its outdoors its more tricky as the water / nutrient uptake changes throughout the day. If you enjoy experiments, track the quantity and ppm of the run off (hourly, dawn to dusk) of an outdoor dtw system in summer. Be sure to log the time, air temp, rh% and ideally light intensity at the plant canopy with each measurement. The day you spend gathering this data will be more than offset by the knowledge and insight you gain from it :wink:

If you have a reasonable quantity of production II recommend to you that make a measure of the volume of water that you input an the final result in a lapse of 5 days with the lowest Nutrients input in order to know how much water your plants take in the lowest EC concentration. And then you can make another experiment with the normal Nutrients mix. And you will know how it’s the relation of water uptake depending the EC concentration.

Thank you guys for the tips! I’ll have a look at it. I hope this will solve my problems.