A chiller is a compressor-based refrigeration unit, like a small air conditioner for water, that pulls heat out of a reservoir. Solution is pumped through the chiller's heat exchanger and back, or a coil is placed in the tank. Units are rated by cooling capacity (watts, BTU/h or horsepower fractions) and by the volume they can handle.
In practice
Chillers matter most in DWC, RDWC and aeroponics, where roots live in solution. Cool water holds more dissolved oxygen, and warm solution above roughly 22-24 °C (72-75 °F) is strongly linked to Pythium root rot. Size the chiller for the room's heat, not just the reservoir volume: lights, pumps and warm air all add heat. Place the unit where it can exhaust its own heat outside the grow, and insulate lines and buckets.
Frozen water bottles are a short-term emergency fix, not a substitute.
Don't confuse with
- Air conditioner: cools air; may help, but solution can still warm from pumps and lights.
- Heat exchanger coil: one part of a chiller setup.
DWC (deep water culture) suspends a plant's roots in an aerated nutrient solution, typically in a bucket with a net pot lid and an air stone.RDWC (recirculating deep water culture) links several aerated buckets to a central control reservoir, pumping solution through all of them to keep conditions uniform.Aeroponics grows plants with roots hanging in air inside a dark chamber, wetted by sprayed nutrient solution; low-pressure (LPA) systems use ordinary pumps and spray heads.A genus of oomycete water moulds, such as Pythium myriotylum and P. aphanidermatum, that cause brown, slimy root rot, especially in warm hydroponic systems.Decay of roots by pathogens such as Pythium, Fusarium, Rhizoctonia or Phytophthora, usually triggered by low oxygen, heat and waterlogging around the roots.An exhaust fan pulls air out of the grow space through ducting, removing heat, humidity and odour and drawing in fresh air.A reservoir is the tank that holds a system's water or nutrient solution, the place where pH, EC, temperature and oxygen are measured and adjusted.Dissolved oxygen (DO) is the amount of oxygen gas held in water or nutrient solution, measured in mg/L, and roots need it to respire and take up nutrients.
