[SOLVED] AeroPonics water nutrition-level sensors

[zainka]

Hi

My summer project this year will be an Aeroponics based greenhouse. Very basically this means that the roots of the plant you are growing suspends into thin air only and for the plant to get its nutritions you have to spray it as a nutrition rich water solution onto the roots using micro foggers (drip water systems) or similar either at low or high pressure,

Now, having control on the nutrition levels, water conductivity, ph and oxygen level in the water sprayed onto the dangling roots is the most crucial point to have at-least some success. Not to much and not to little. That calls for some electronics You may read more about these requirements here and here if you think this is interesting.

What I would like to hear about from you is if you know about other DIY project, or if you have some similar projects yourself, where making ones own electronics is part of the project etc. Especially I need to investigate more on sensors for measuring EC or epsom salts, magnesium and calcium nitrate, in addition to oxygen and Ph. Also, how do one determine if the water has been contaminated? (I guess that calls for extra sensors.) . I wanna do my own HW cause I believe that this will be the most efficient way to learn the most and in addition its fun.

Thanks in advance

 

[BradtheRad]

Certainly it must be difficult just to detect whether tiny roots are moist or dry. To detect presence of chemicals, might be possible via spectroscopy of some sort.

I tried hydroponics once. I planted vegetable seeds in trays of clay cat litter. I purchased a Gro-light tube and suspended it above the trays. Using a timer I had it on 18 hours per day. Once or twice a day I poured on a cup or two of Miracle-Grow solution. Excess liquid was allowed to drain through the litter and out of the trays.

Results were disappointing. Hardly any seedlings came up. Maybe one or two plants survived. I was unable to know whether the roots were waterlogged or dry. There's a chance the clay litter was not entirely chemically neutral as a growing medium. Or maybe it acquired a high concentration of chemicals as a result of nutrient solution evaporating from the surface.

 

[zainka]

I guess its not meant to be easy, but thats not why we do this, we do it because its hard...

I do not expect to succeed at first try, (even though theres no reason why not except a million), but First of all I need to have control on the conductivity in the water and the Ph. Thats the two main sensors in the system. Here I may use technology from Aquariums. Found the following project for ardunio: **broken link removed**

They use standard Ph and conductivity sensors and it is what I was looking for as a starter and theres a ton of these sensors at ebay to look at, in addition I need temperature sensors and moisture sensors inside the Aeroponics chamber (it will give a clue if the roots a re dry or not.) as a minimum. Then of-course there is motor controller to the pump which should have a backup pump to fall in if the main pump fails. One of the most common source of failure with Aeroponics is pump failure with the following root dryout.

To prevent root dryout one could also use high pressure foggers. The dropplets will have a higher speed and this will ensure that the entire root bundle gets wetted into the very center of the bundle and not only the outside of the bundle which might be the cause if using low pressure. However, the nozzles are more expensive and have a higher failrate.

Lots to think of, as you may see, but fun.... for now atleast

 

[zainka]

Just for the records:
The following link gives documentation for a range of sensors that might come in handy for Aeroponics designs. It more or less solves my search for sensors so I marks the thread solved, but feel free to give link to other DIY Aeroponics projects.

Found this trough open aquarium:
https://www.libelium.com/development/plug-sense/documentation/

 

[Kajunbee]

I did not know that bacterial contamination could be sensed other than looking through microscope. Supposedly there is new technology that that uses a graphene or graphite sensor to sense water contaminants. The technology is based on how field effect transistors operate. From what I understand these materials are far more conductive than other materials which I think improves the sensitivity. I believe it's in experimental stage still which doesn't help you any but maybe something to look at in future.
Something else to consider is using low pressure mister that operate off of typical household water pressure which ranges between 40 and 60 psi. There are downsides to low pressure misting but the plus side is no pump to fail or consume energy. The less moving parts the better if your looking for it to be profitable.

 

[zainka]

I guess one could measure CO and other bi products / gasses as sideeffects to bacterial activity. There will always be some activity but an explode in bacterial growth could be determined by an abnormal increase and level of these biproducts.