Heating the reef tank can be done a number of ways. These vary from cable heating to electric heaters.

Alternatively, and more practically, heating a marine tank can be accomplished just as effectively with submersible stick heaters.

These heaters should be saltwater proof, have some type of adjustment dial on the top that controls the set point desired, and have a visible temperature scale so that the set point can be easily set. Heaters that are not saltwater proof, such as ones used primarily for freshwater aquariums, will start to corrode when the saltwater from the tank comes in contact with any exposed metal part of the heater and thus should be avoided to prevent contamination of the water.

How much power?

The size of the heater to use will depend on the amount of water in the system, the particular room where the tank will be placed, and the size of the trickle filter or sump filter used. For example, most 75 gallon reef systems will only need one 200 watt stick heater. This will provide at least 2-1/2 watts per gallon of water in the system.

For tanks located in rooms that are susceptible to colder than normal conditions, 3 to 4 watts per gallon should be the rule. In this case, the wattage should be split between two or more stick heaters. The reason is two fold: first, if the single higher wattage heater “sticks” and does not automatically turn off at its set point, the inhabitants of the reef tank will not only be stressed, but most likely “cooked”, and second, stick heaters with this much wattage may not fit.

Heaters with greater wattages in excess of these amounts are unnecessary.

Where to Place the Heater?

The stick heater can be placed in the tank, but should ultimately be placed in the sump of the trickle filter or sump filter so that when the water goes through the trickle or sump filter it can be heated, if necessary, and be dispersed throughout the tank as it returns via the main water pump. Furthermore, by placing the heater in the trickle or sump filter it can be effectively hidden out of sight.

Place the stick heater of choice in the aquarium across the back of the tank with its suction cups along the rear glass at a slight upward angle. The heater should be set so that it cannot be seen once the rock has been added when viewing the tank from the front and high enough so that it does not touch the sand substrate.

Remember to NEVER plug a heater in an electrical outlet if it has not been in the tank for more than 10 to 15 minutes because it may become damaged or ruined.

Use a thermometer

Finally, attach a digital thermometer on one of the tank sides. We have chosen to use a digital thermometer instead of a floating glass thermometer because glass can shatter and contaminate the tank with mercury.

Attach the “stick-on” thermometer to the outside tank glass in a spot that does not substantially block the view of the mini-reef on either the side or the front. Depending upon your personal preference, either a vertical or horizontal type digital thermometer can be purchased.


  • My recommendation is to use “several” individual heaters and not just one. If you do so, and one heater fails for instance, the others will still be working and the temperature will be maintained, or nearly so.
  • A good recommendation for the wattage of the heater the aquarist selects for their aquarium is 3-5 Watts per gallon of aquarium water.


Please enter your comment!
Please enter your name here