Keeping Reef Tank Temperature Stable

Reef fish and corals tolerate a range near 76°F to 80°F (24°C to 27°C) but suffer when temperature jumps several degrees in a day. Use a reliable heater sized for your volume and verify with a separate thermometer.

Summer room heat may require fans, chillers, or lowering lighting intensity. A cheap clip fan blowing across the surface can drop temperature one or two degrees in small setups.

If the heater sticks on, livestock dies fast — use an controller if possible. Log daily highs and lows during heat waves in ReefDiary; patterns show whether you need permanent chiller investment.