Hello: I am interested in making a sensor/controller for a small hydroponic grow (using deep water culture) where the roots of the individual plants are immersed in the water/nutrient solution. The solution would be aerated and circulated using two aquarium-type aerators (with micro bubbler stones).
I also intend to use the same Arduino (probably a Nano) to control the lights as well for the appropriate photoperiod.
My questions are:
What are the best Arduino-compatible: 1) pH sensors; 2) dissolved Oxygen sensors; 3) Water level sensors and 4) water temperature sensors?
At this point I don’t plan to do any control functions, but simply want to display the parameters from the sensors described above, on a small OLED display so I can make any corrections/adjustments as necessary. I would like to get as many off-the-shelf items as I can. In a few cases, (like the water level sensor) I feel I could make my own but I don’t want to spend a lot of time on that.
Would anyone care to make some suggestions or recommendations?
Are you sure that you can afford the best sensors, these can get quite expensive.
I think all sensors are Arduino compatible, so your best plan is to use the internet to find out how these sensors work, and what interface they present to the Arduino. However these sorts of sensors are not fit and forget, they need tending. Like a Ph sensor needs buffer solutions to calibrate the readings every couple of hours or so.
We use the Atlas Scientific sensors and interface modules.
They are mid range in price, but they "just work" when used together. This allows you to get on with what you want to do instead of wasting hours trying to get cheap stuff to work.
I don't think you can get a PH sensor that remains submersed, for long periods. Although if you find one I would like to know.
As far as the Dissolved Oxygen Sensor is concerned, I don't see the point, given you are not doing any control and regardless it is waste of money for a hydroponic application.
I just use cheap sensors given they work, without any messing about. A capacitive sensor for water level and temperature sensors for the water.
I have 3 hydroponic units running, 2 of which are of the similar type to what you are using. The plants are on an inclined bed with water pumped onto the gradient into a reservoir tank, which just has a fish tank oxygenator in it. The third is similar but for 40 small plants with a stop start water feed.
As far as sensors are concerned all you need is a water level sensor and a temperature sensor, then measure the PH with a hand held meter once every so often.
As an observation, I find the PH is related to the height of the water, where the PH changes as the level drops.
I have seen hydroponic units that use a sprinkler to douse the roots, which allows the plant to get water and air easily, without drowning the roots.
Are you fixed on hydroponics? NASA is using aeroponics to grow for extended space flights .. it is a simple concept ... I'm hoping to try it this next spring...
The misters are only turned on a few seconds to ensure the roots stay moist.
Hi and thank you for the illustrations! My original intent was to use the idea of employing sprayers (like in the illustration you sent for “Aquaponics”), but I am reluctant to go that route because of one reason only: For awhile at my previous residence I got some drip lines or drip dispensers (to dispense water) for use on outside plants and invariably the drip devices would get clogged with sediment or some debris that would render them useless. That is the only reason I am not choosing to go the route of the deep water culture because I am afraid that the nozzles of the sprayers can easily become clogged. I understand that DWC is fraught with its own issues, but I think they might be more easily managed..
Further though I know that I will be checking my plants daily, I am afraid to allow the roots to have any length of time in an un irrigated state.
My 40 plant hydroponic system (Similar to hydroponics drawing, which uses water pipes, with rock wool in plant baskets) runs water/nutrient over the roots every 2 hours for 15 minutes.
I don't use an air pump, given the roots are exposed to air anyhow and there is no problems with dirt ingress as the feed pump is through a filter from an enclosed reservoir.
Thanks everyone for the great feedback! So much of my plans to automate were really unnecessary and I appreciate bringing me back to reality (I.e. the lack of a need for constant pH monitoring, etc).
