Aquarium Setup
Heaters & Thermometers

Heaters are a vital piece of equipment for all tropical aquariums.

The water temperature in tropical aquariums should never drop below 74º F. The average temperature for most tropical aquariums is 76º to 82º F. (Note: These temperatures do not apply to the goldfish species. They can tolerate colder water temperatures.)

PETCO sells two types of aquarium heaters: submersible and non-submersible.
Getting Started with a Freshwater Aquarium
1. Aquarium Water
2. Choosing Freshwater Fish
3. Aquariums & Stands
4. Hoods & Lighting
5. Heaters & Thermometers
6. Air Pumps & Accessories
7. Filters
8. Gravel & Décor

Heater Type Characteristics PETCO Suggestions
  • Has advanced thermostat
  • Is stable enough to function in a horizontal or vertical position
  • Allows the heat to be distributed more evenly
  • Keeps the water temperature within one degree of the setting

Marineland Stealth Submersible 50 Pro-Heater
Marineland Stealth Submersible 50 Pro-Heater

Aqueon Submersible Aquarium Heaters
Aqueon Submersible Aquarium Heaters

  • Hangs on the back of the aquarium
  • Is not 100% waterproof
  • Is less expensive
  • Does not have a very advanced thermostat
  • Needs constant adjustment
  • Must be operated in a vertical position

Here are some tips to remember about heaters:
  • When removing your heater from the aquarium, unplug it and leave the heater submerged for 20 minutes before removing.
  • Always unplug the heater when performing maintenance such as partial water changes.
  • Make sure the water level in the aquarium is the correct level to avoid damaging the heater.
  • Allow between 3-5 watts per gallon.
  • Place the heater where optimum water circulation takes place, but avoid undue splashing such as near air stones or return tubes.
  • When raising or lowering the water level, do so gradually to avoid undue splashing.

Monitor water temperature with a thermometer. Adjust water temperature gradually to avoid stressing the fish. Five degrees per 24-hour period is recommended.
Thermometer Type Characteristics PETCO Suggestions
Liquid Crystal
  • Is the best type for glass aquariums
  • Sticks on the outside of the aquarium
  • Is accurate and easy to read

ATI Aquarium Thermometer
ATI Aquarium Thermometer

  • Floats in the water
  • Sinks to the bottom of the aquarium
  • Clips onto the side of the aquarium

Petco Glass Thermometer
Petco Glass Thermometer

Thermometers should not be placed near the heater because proximity to the heater will result in a higher reading.

Step 6: Air Pumps & Accessories