Reservoir Temperature

Marijuana Horticulture

by Jorge Cervantes

The temperature of the nutrient solution should stay between 60-75F. However, nutrient solution will hold much more oxygen at 60F than it will at 75F. never let the nutrient solution temperature climb above 85F. Above 85F, the solution holds little oxygen. Roots are easily damaged by temperatures 85F and above. Heat damaged roots are very susceptible to rot, wilts, and fungus gnat attacks.

To save energy and money, heat the nutrient solution instead of the air in the room. Heat the nutrient solution with a submersible aquarium heater r grounded propagation heating cables. The heaters might take a day or longer to raise the temperature of a large volume of solution. Do not leave heaters in an empty reservoir. They will soon overheat and burn out. Aquarium heaters seldom have ground wires, a seemingly obvious oversight. But I have yet to learn of an electrocution by an aquarium heater. Avoid submersible heaters that give off harmful residues.

When air is cooler than water, moisture rapidly evaporates into the air; the greater the temperature differential, the higher the relative humidity. It will also promote the uptake of nutrients.

An air pump submerged in the reservoir not only aerates the solution, it will help level out the temperature differential between ambient air and reservoir.