Reservoir or root zone water warm (above 23 °C / 73 °F)
Rises through the light period and in summer; worst in small reservoirs near lights or pumps..
- Also called
- res too hot
- warm reservoir
- water temperature high
- reservoir temp 26
Likely causes, most likely first
Ranked for this sign on its own. Your stage, medium and readings change the order, so run the checker for your plant.
LikelyReservoir or root zone too warm
Fix: Keep solution at 18-22 °C (64-72 °F): insulate and shade the reservoir, move it off the warm floor or away from the light, use a chiller or frozen water bottles in an emergency, avoid submersible pumps that add heat, cool the room.
Recovery: Solution holds below 22 °C through the light period; new white roots in 3-5 days.
How to confirm it
- Measure reservoir and root-zone temperature at the end of the light period. Measure the solution in the reservoir and in the root chamber or bucket, at the warmest time of day. Target 18-22 °C (64-72 °F). Above about 23-24 °C (73-75 °F), dissolved oxygen falls and Pythium risk rises; below 16 °C (61 °F) uptake slows.
- Dissolved oxygen check. Measure DO with a meter in the root zone, or check the system: air pump running, stones bubbling evenly, return water splashing, no dead spots. Target 6-8+ mg/L. Without a meter: if stones are clogged or the pump is undersized for the volume, assume low DO.
Less likelyPump, timer, air or emitter failure in a hydro, aero or drip system
Fix: Restore flow or air immediately: check power, timer, float switches, filters and nozzles. Mist exposed roots by hand or lower plants into solution while you fix it. In HPA and NFT, fit an alarm and a backup pump; roots die fast when misting or flow stops.
Recovery: Plants regain turgor within hours if roots were not dead; brown, collapsed roots mean rot risk next.
How to confirm it
- Check pumps, timers, nozzles and drippers. Watch one full cycle: the pump starts on time, every nozzle mists or every dripper delivers, NFT channels have flow end to end, air stones bubble. Clear clogged emitters and filters. In HPA, a failed pump or blocked nozzle can kill exposed roots fast, so check this first when plants on one system wilt together.
Look for
Thermometer reading in the reservoir at the end of the light period..
The full guide: Brown roots in hydroponics (DWC, RDWC, NFT): a differential
Guidance, not a guarantee. The checker weighs common causes against what you tell it; confirm with the tests before you treat, change one thing at a time and watch the new growth.
