You need to consider both the air and water temperature of your growing space. Place a thermo-hygrometer in your room; this handy tool measures both temperature and humidity. Aim to maintain an air temperature of 24–27°C. You can regulate this using fans and air conditioning units. Place a hydroponic thermometer into your reservoir. You want to maintain a water temperature of 18–20°C. Use ice packs or hydroponic coolers to regulate this if necessary.