After the vital matter of lighting, there follows a second issue, which is no
less important: heating. You must first establish your requirements. The aquatic
animals and plants in tropical regions live in warm water in which the temperature
hardly varies over the course of the year. Tropical aquariums must therefore be
heated, with the temperature guaranteed at around 25-26°C, or even 27°C for sea
water. These temperatures can be maintained with a watertight electrical heater
connected to an adjustable thermostat that switches itself off once the desired
temperature has been achieved. When the latter goes down by 1°C or less, the thermostat
reconnects the current and the heater starts to heat up again. Classic ther mostats
for aquariums allow the temperature to be regulated with some precision, to around
More precise electronic thermostats are also available. These react to variations
of the order of 0.1°C, but unfortunately they are more expensive.
Once you have established your requirements, the next step is to choose the problem
of the heating equipment. There are independent elements available, attached to
a thermostat, but they have the disadvantage of multiplying the number of electrical
connections and cables to be hidden.
Independent thermostat and heater: practical, if you want
to modulate the power of the heating, but unwieldy as regards electrical cables.
Another option is a heater-thermostat - combining both a thermostat and a heater
- which is completely watertight and submergible. This system is becoming increasingly
popular as it is so easy to use. Finally, a less common type of element consists
of a heating cable sealed inside a flexible tube, which is placed in the sediment.
Some aquarists, however, think that the diffusion of heat via the bed damages the
roots of plants. Furthermore, there is a danger that the cable may be partially
unearthed by a burrowing animal in the tank.
HEATING FOR BEGINNERS
A heater-thermostat is the most practical solution for beginners. Make sure to
choose a model in which the temperature readings are clearly visible. They often
have a small light which indicates when the element is heating up. The power depends
on the volume of water the aquarium will hold: calculate around 1 W/liter, which
means that a 100 liter tank requires a heaterthermostat of 100 W.
A heater-thermostat must always be totally submerged.
The heating power level
The temperature in an inhabited room - a lounge or bedroom - rarely falls below
17°C. If an aquarium is installed, the heating must be sufficiently powerful to
go from this room temperature, which will be the same as that of the unheated tank,
to one of around 25-26°C.
A power level of 1 W/liter is generally sufficient to ensure this increase in
temperature. Therefore, 100 W will be required for a 100 liter aquarium, and this
will also suffice for a 150 liter tank. In an uninhabited, and usually unheated,
setting, such as a garage, cellar, or loft, a tank sometimes requires up to 2 W/liter,
but rarely more than this.
The thermostat must be placed some distance away from the
heater for an adequate control of the temperature.
There is a sufficiently wide range of heating devices and power levels to cover
all your needs for volumes up to 500 liters (25, 50, 75, 100, 150, 200, and 500
W). Beyond that, it is cheaper and easier to heat the entire premises (as in the
case of clubs and public aquariums) than to heat tanks individually.
Installing the heating equipment in the aquarium
It is important that the heat discharged by the heater is spread throughout the
aquarium, in order for the temperature to be relatively uniform. Therefore, put
the heaterthermostat in a turbulent spot, to help spread the heat and prevent any
areas being warmer than others. Another alternative is to distribute the heat by
dividing the overall intensity - two heat sources of 100 W instead of a single one
of 200 W, for example - but this entails more cables to hide, both inside and outside
the aquarium. The thermometer must be kept away from the heat source, to avoid being
directly affected by it.
Sometimes, the glass protecting a heating apparatus may break, especially when
you are handling it, and so it must be replaced. However, before plunging your hand
into the aquarium, it is essential to unplug the heating system, as there is a risk,
however minimal, of getting an electric shock - water, particularly salt water,
is an excellent conductor of electricity. The heater's heating wire can break, meaning
that the water is no longer being heated and gradually cools. In this case, an internal
black deposit appears in the heater, or on the heater component of the heater-thermostat.
Another common problem is the blocking of the thermostat in the heating position:
the metal strip "sticks" to its contact, the element continues heating, and in a
few hours the temperature of the tank can soar above 30°C. This can occur with well-used
thermostats, although the problem can be avoided with a second thermostat, inserted
as a safety measure between the first and the mains supply. If in doubt, consult
a qualified electrician who has experience in dealing with domestic aquariums or
your local supplier.
A diffuser placed under the heater-thermostat distributes
heat throughout the aquarium.