Reef Tank Temperature: Stability, Chillers, and the 78F Sweet Spot

Reef stability matters more than the exact target. Most experienced reefers run 77–79°F with daily variance under 1°F.

When you need a chiller

If your tank exceeds 82°F in summer or your room AC cuts out at night, a chiller becomes mandatory. Powerheads and pumps add 1–3°F of waste heat.

Lid off + cooling fan blowing across the surface drops temperature 2–4°F via evaporation. Just upsize your ATO reservoir.

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