Question: How to measure nutrient concetration in hydroponic system?

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Aleksi12358 asked on July 07, 2018 21:45
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Reason I want to do this is so that I can measure plants uptake of different nutrients and add right nutrients to reservoir with automated nutrient dispenser. Plants I want to study are salad, tomato, chili peppers, cucumber and strawberry. Maybe I will grow some other food plants later but these are what I would start with.

Is it possible to use spectrometer for analysis of nutrient concentration in solution? I want to measure as many different nutrients as possible. If it is possible could someone link me some literature about using spectrometer for nutrient concentration analysis?

I am open to other analytical methods to measure nutrient uptake if anyone knows better ones. I think ion selective electrodes with artificial neural network would be quite cool for analysis of nutrient solution but it seems to be too expensive for me as single electrode is multiple hundred €. I am looking something hobbyist can buy or build with max ~1000€.

Thank you.

hydroponics fertilizer nutrients nutrient uptake

question:spectrometry question:water-quality question:general question:hydroponics question:fertilizer


Hi, which nutrients are you hoping to measure?

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I would like to measure every plant nutrient from macro to micro but I think macro nutrients(nitrogen, potassium, phosphorus, sulfur, calcium and magnesium) will be enough for start.

I did find one article about using infrared spectroscopy to measure nutrient levels. It works for macro nutrients. Here is link to it: Is it possible to turn public lab spectrometer to infrared spectrometer?

If there is possibility to use Open lab spectrometer to measure nutrient levels. Could it work that I make hole in bottom of cuvette and lid that has hole and run nutrient solution from reservoir trough cuvette back to reservoir? This way I could gather real time data. Real time data is not necessary but I would like to automate gathering of data at some point and this seems to be simplest way.

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The public lab instrument will cover a part of the NIR. Unless you can find very cheap used FTIR, the cost of the instrument will far exceed your budget.

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3 Answers

I have very little experience with soil testing. So the local extension agent was called. He suggested the lamotte NPK test kits. One that will do 50 tests and costs about $30. He hadn't used it on hydroponics. But at that cost, it's worth a try. It's a visual test. No instrumentation is needed. By the way, amazon also lists a lamotte total test kit that will analyze for 14 different characteristics ( but only once), also for about $30. Its also for soil, not hydroponics.

Good luck

Hi, just for starters there are a couple interesting projects related to nitrate detection here:

There's also this related question:

This page

But this seems the most promising!! --

Also Markos, from the spectrometry mailing list, chimed in with:grinning:


I apologize for sending here a reply to the question proposed at:

but I tried to login to post an answer but I forgot the password and tried to reset but I didn't receive a confirmation email.

So I am sending here the links that might be useful for the question proposed:

The system stores the different reagents in syringes.

And the reagents are added in a mixing syringe containing a
magnetic stirring system and the color generated (depending the composition) 
is analyzed by a camera.

So far, as I understand it, the whole system is controlled by a

A project to inspire other projects on the Water theme.

Best Regards,

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