We recommend that nutrient solutions temperatures should be between 68°F and 72°F. Any warmer than this and you will begin to deprive the plant roots of essential oxygen as warm water can hold less oxygen than cooler water. Water chillers are suitable for lowering temperatures in reservoirs, hydroponics systems, or fresh and salt water aquariums. Select from EcoPlus water chillers, EcoPlus commercial water chillers, Active Aqua water chillers. Available from 1/10 HP to 3 HP.