Tetra 100W Submersible Aquarium Heater

The Tetra 100W Submersible Aquarium Heater (model 26446) is a preset heater for 10 to 30 gallon aquariums. An electronic thermostat keeps the water at a consistent 78 degrees, and the heater is UL Listed.

Preset at 78 degrees

78 degrees suits most community tropical fish, including tetras, livebearers, rasboras, gouramis and many catfish. With no dial to adjust, the heater is quick to set up and difficult to mis-set. If your fish need warmer or cooler water, choose an adjustable heater instead.

Indicator light

A red light shows when the heater is warming the water; green means it is on standby. A quick glance tells you it is working.

Installation

Attach it to the aquarium wall with the suction cup. Place it where water moves past it, ideally near the filter outflow, so warm water spreads through the tank instead of pooling.

Sizing

• 10 to 20 gallons: comfortable margin in most rooms
• 20 to 30 gallons: fine in a warm room; consider a second heater in a cold one

Safe use

Keep it fully submerged when plugged in, unplug it before water changes and let it cool before lifting it out. A separate thermometer is a good idea to confirm the tank holds the expected temperature.

Compare

For an adjustable alternative in a similar size, see the hygger 100W heater with digital control. For a higher-end adjustable heater, the Fluval E series adds a display and alarm.

Who it suits

Beginners and keepers of standard community tanks who want a reliable, no-fuss heater from a familiar brand. It is a good choice for a classroom or office tank where you do not want anyone adjusting the temperature. Tetra lists the warranty details on the label.

Because the thermostat is electronic rather than a mechanical strip, the temperature tends to stay steadier through the day, with fewer small swings as the heater cycles.