Collection: Thermometers

Know the Temperature, Not the Setting

A heater dial tells you what the heater thinks it is doing. A thermometer tells you what the water is actually at, and the two part company more often than people expect. It is the cheapest instrument in the tank and usually the first thing to reveal a heater going wrong.

Types in This Collection

• Floating thermometers — low-cost analogue units, some with a suction cup so they stay where you put them.
• Submersible digital thermometers — probe in the water, display outside the tank.
• External digital thermometers — mount on the outside of the aquarium with nothing sitting in the water.

Run two of them. Cross-checking a pair is the only reliable way to notice one drifting, and a stuck reading looks exactly like a stable tank right up until something dies. Take readings away from the heater and away from the return flow, so the number reflects the tank rather than its warmest corner. Questions? Email info@jlaquatics.com.