How To Choose Aquarium Heating.
Tropical aquarium systems, both freshwater and Marine, seek to duplicate as faithfully as possible the environment in which a particular variety of fish has evolved. One of these environmental parameters is temperature. Whilst seasonal influence in the natural environment does mean that most fish species have quite a tolerance to temperature fluctuations within a broad band, it is desirable in the aquarium, to keep temperatures as stable as possible. To achieve this an aquarium heater is used.

What Is An Aquarium Heater.
An aquarium heater is a device that generates heat and maintains temperature within a pre-set zone. It can do this because a modern heater is a dual unit that incorporates both the heating element and a thermostat control device. The thermostat can be set to a pre-determined temperature and this will activate the heating element if the temperature falls below the pre-set target. Conversely, the thermostat will cut off the heating element if the temperature rises above that set. The combined heater / thermostat unit is housed in a glass tube shaped like a long cigar with the heating element in the bottom section and the thermostat above.

Choosing An Aquarium Heater.
Aquarium heaters are available in a range of wattages, the wattage will determine the heat output of the unit and therefore the size or volume of the aquarium for which it will be suitable. The following is a basic guide to which heaters to choose for various aquarium sizes.

For larger aquariums use more than one unit. It is important to choose a good quality heater as if it fails the aquarium could either over heat or chill off with disastrous consequences for the inhabitants. Some heaters are now available with guarantees up to five years (Ultratherm) but even standard twelve month covered ones are ok if they are produced by one of the better-known manufacturers. It is recommended that units with a twelve-month guarantee be replaced every three years. It is worth noting that manufacturers will not accept consequential loss even if a heater fails within the guarantee period, it is only the unit itself that is guaranteed.

Positioning An Aquarium Heater.
An aquarium heater should be positioned on the rear glass of the aquarium at roughly an angle of 45 degrees. This will allow the heat to rise and dissipate from the heating element without adversely affecting the thermostat unit. Some heaters are designed to be fitted vertically without affecting the thermostat reading. The heater is attached to the glass with suckers that are usually supplied with it. Guards are available to cover the heating element so avoiding burns to fish (Or reptiles such as Terrapins) that may come into contact with it. It is not necessary to guard a heater in the average community aquarium. Heaters have a neon light indicator that illuminates when it is giving off heat so ensure that this is facing forward and not obscured.

Adjustment And Maintenance Of Aquarium Heaters.
Adjustment and setting of the desired temperature is done by gently twisting either the very top part of the unit or a protruding cylindrical knob. Twisting clockwise will increase the temperature setting and anti-clockwise decrease. As part of the standard four weekly aquarium maintenance the heater should be wiped gently with an algae pad to remove algal and other deposits. Always isolate the heater from the mains supply before attempting any adjustment or cleaning.

Other Types Of Aquarium Heater.
Some manufacturers such as Rena (Rena Cor) make wire-heating elements that are affixed to the internal bottom of the aquarium and covered by the substrate layer. Carbon heat mats similar to the ones used for vivarium heating but of a higher wattage, for fixing to the outside beneath the aquarium, have also been available (Ultratherm). Both these systems dissipate their heat output over the entire surface area of the element over a large part of the base area. Possible benefits would be very even heat distribution so avoiding temperature “dead spots” and better plant growth. These alternatives, however, have not captured the aquarist’s imagination to any great degree and remain an option not taken up by many. Heat exchangers are also used on some aquarium systems but almost exclusively in professional commercial sector.