Is 78 Degrees Too Hot for a Hydroponic Nutrient Tank?

Growth Regulation

• Controlling the temperature in the hydroponic nutrient tank is an effective means of regulating the growth of the plants in the system. According to a study by the University of Arizona, seeds in systems with high water temperatures do not germinate as fast as those at temperatures below 77 degrees Fahrenheit. Plants growing in warmer systems are also prone to bolting, effectively making the plants useless for anything but seed. Keeping the nutrient solution cool helps with germination while reducing bolting problems regardless of the air temperature.

Oxygenation

• The temperature in your nutrient tank has a direct effect on how much oxygen the water is able to hold. The higher the temperature, the less oxygen is in the solution. At the same time, plants increase their rate of respiration as the temperature increases. This means that water at 78 degrees Fahrenheit holds less oxygen than water at 68 degrees Fahrenheit, while plants at 78 degrees Fahrenheit require a significantly higher oxygen level than they do in cooler water. Unless you increase the oxygenation of the nutrient solution, the plants will struggle to survive.

Symptoms of Trouble

• If the nutrient temperature increases but oxygenation does not, the plants will begin to show signs of distress. The first sign is intermittent wilting, usually during the hottest part of the day. If the problem continues, the plants will begin to display other problems including permanently drooping leaves, yellowing of the leaves, stunted growth and roots that stop growing and eventually die back. Toxins and bacteria can invade the plants in an oxygen-starved system, and typically once that happens, the plants cannot be saved.

Evaporation

• If the nutrient tank temperature is high, the solution will evaporate faster than it would at lower temperatures. While 78 degrees Fahrenheit is not necessarily too hot, it is high enough that you must take evaporation into account. Check your system levels every day and add plain water as needed to keep the nutrient level up. You may need to replace the solution often to avoid a buildup of salts in the system.