Why Water Temperature Runs the Root Zone
Roots live in the nutrient solution, and that solution’s temperature decides how much dissolved oxygen the roots get and how fast pathogens grow. The sweet spot for most crops is roughly 65–68°F (18–20°C). Let it climb into the 70s and oxygen drops while root-rot organisms thrive; let it fall too low and growth slows. A chiller keeps the reservoir locked in the band the plants want.
Where the Heat Comes From
Indoor grows are full of heat sources that end up in the water: grow lights, pumps that add friction heat, and warm ambient air in the room. The chiller has to remove all of it to hold setpoint, which is why sizing for the lit, peak-load condition matters — not the lights-off temperature.
- Reservoir / nutrient solution — the primary thing being chilled.
- Recirculating DWC and NFT systems — large water volumes that gain heat continuously.
- Vertical farms — many tiers, high light density, large combined load.
Material matters with nutrients. Nutrient solution can be corrosive to bare metal. Look for a chiller with a corrosion-resistant evaporator (for example titanium) for direct contact with nutrient water.
Sizing the Chiller
| Factor | Effect on size |
|---|---|
| Reservoir volume | Larger volume needs more capacity to pull down and hold |
| Lighting load (W) | Lights are the biggest heat source — size for lights-on |
| Pump heat & ambient | Add to the total load |
| Target temperature | Lower setpoints need more capacity |
Use the sizing tool with your reservoir volume and target temperature, then we will sanity-check it against your lighting and room load.
FAQ
What temperature should my nutrient reservoir be?
For most crops, about 65–68°F (18–20°C). That range keeps dissolved oxygen high and suppresses root-rot pathogens that thrive in warmer water.
Why does warm water cause root problems?
Warmer water holds less dissolved oxygen and lets pathogens like Pythium multiply faster, so roots suffocate and rot. Chilling the reservoir keeps oxygen up and disease down.
Do I need a special chiller for nutrient water?
Nutrient solution can corrode bare metal, so choose a chiller with a corrosion-resistant evaporator such as titanium for direct contact with the water.
See the full Horticulture page for system options.
Not Sure What You Need?
Tell us what you are cooling and we will figure out the right chiller for you. No jargon, no catalog. Just a straight answer.