Hydroponic CO2 and/or pH Controller in the Water?

by Vincent
(Netherlands)

I have a little hydroponic setup where my pH creeps up very quickly. It changes from 5.8 to about 7 within one day, and I have to add pH down for vegetative growing every day. So, to keep the right pH, I have to adjust this twice a day.

I've heard they sell pH and CO2 controllers for aquarium's, and was wandering if this could help to maintain the correct pH level in the reservoir. Best regards, Vincent.

Answer: Vincent- pH controllers are usually kind of expensive. The ones I have seen have a small reservoir of pH down as well as a monitoring sensor. Whenever the pH creeps up too much, the device delivers a small amount of the pH down to the nutrient reservoir automatically.

More recently, I have had two different visitors mention a device that adds CO2 to the water to control it's acidity (pH). My gut feeling is that it would work, as fish aquarium pH is usually in the same range as a hydroponic system's pH....although I don't have any personal experience with this device, and am not sure how well it works in a hydroponic situation. However, I do have a couple of other ideas that may correct your problem without very much additional expense.

A well designed hydroponic system should contain about 3/4 gallon to 1 gallon of nutrient solution per plant. I use this as a minimum guideline whenever I am putting a homemade hydroponic system together. The volume of nutrient solution acts as a buffer that slows down the speed at which the pH will change. The more solution, the more buffer you have. If you are using less nutrient solution than this, it may be part of your problem (and part of the solution).

Also, different brands of hydroponic nutrients vary considerably as far as what pH they mix up at and how quickly the pH begins to change once mixed. Earth Juice, for example, requires a LOT of pH adjustment. You may be able to correct your problem by changing to a different brand of nutrients. A product line called Canna Bio, for one, mixes up at just the right pH and requires almost no adjustment from day to day! This not only eliminates the need for a controller, but also the need to buy so much pH down.

I hope this helps you out Vincent, and Happy Growing!