Aquarium Heater Guide



Aquarium heaters are a very useful tool in keeping Amphibians. They are the preferred heat source for aquatic, semi-aquatic and larval Amphibians and can be used as a background heat source in paludariums and terrariums with large water areas. Aquarium heaters have a number of advantages over under tank heat mats, heat cables and heat bulbs in these set ups; one being that the majority of aquarium heaters have built in thermostats so do not require a second more expensive devise in order to be used and secondly that by heating the water in the terrarium they in turn increase the humidity unlike most other heat sources that dry the air, substrates and decor lowering humidity.

Size Guide

In order to work out the required heater wattage you first need to do 2 simple calculations;

  1. Length (cm) × Width (cm) × Depth (cm) ÷ 1000 = Water volume (Liters).
  2. Required water temperature − Minimum room temperature = Temperature increase needed.

Now you have the water volume of your aquarium and the increase in temperature needed you can use the chart below to calculate the heater wattage required.

Water Volume (Ltrs) 5°C Increase 10°C Increase 15°C Increase
25 25w 50w 75w
50 50w 75w 75w
75 50w 75w 150w
100 75w 100w 200w
150 100w 150w 300w
200 150w 200w 2× 200w
250 200w 250w 2× 250w
300 250w 300w 2× 300w

When large volumes of water are being heated or when a higher temperature increase is required it is advisable to use two lower wattage aquarium heaters (2× 100w = 200w) positioned one at each end of the aquarium, this will provide a more even temperature and in the unfortunate case of one heater failing you have the other present as backup to stop the temperature in the aquarium from dropping too sharply.

Heater Guards

When using aquarium heaters in Amphibian enclosures we always recommend using a suitable heater guard to prevent damage to both the heater and the inhabitants. Large boisterous species are quite capable of dislodging a heater from it’s holder which can leave the heater open to further knocks against the aquarium glass and decor causing damage to the glass cylinder or may even lead to the heater being exposed to air causing it to over heat and crack. Some species, most notably the Rio Cauca Caecilian (Typhlonectes natans) are very fond of coiling themselves around aquarium heaters thus increasing the danger of burns if not properly guarded. I feel that NeWatt heaters deserve a special mention here, constructed with an aluminium and polymer cylinder in a reinforced plastic casing these heaters are virtually unbreakable and are ideal for use in Amphibian enclosures.