Heaters & Chillers Temperature Control Guides

Sizing guides, installation tips, and product reviews for aquarium heaters and chillers. Keep your tank at the right temperature year-round.

Most tropical freshwater fish need water between 76-82°F, and even small temperature swings stress fish and weaken their immune systems. An adjustable heater is essential equipment for any tropical tank. Size your heater at roughly 5 watts per gallon — a 20-gallon tank needs a 100-watt heater.

Chillers solve the opposite problem. Summer heat, reef tank lighting, and warm climates can push water temperatures above safe levels. Aquarium chillers use refrigeration to bring water back into range — critical for coral reef tanks and cold-water species like axolotls.