As
a general rule, the more water a tank holds the more stable the aquatic
environment will be. For example, it will take a 50-gallon tank much longer to
drop in temperature than a 10-gallon tank.
The
same is not true for temperature increases, though, because the aquarium heater
wattage is chosen to match the size of the tank it will be in. The rule of
thumb is five watts per gallon, which will allow the heater to raise the
temperature of one gallon of water by one degree Fahrenheit in one hour.
Thus,
a 10-gallon tank would use a 50-watt heater and a 50-gallon tank would use a
250-watt heater. For larger tanks it is often necessary to use more than one
heater to achieve the desired wattage.
In
fact, using more than one heater is actually a good idea for any size aquarium
in terms of safety. When two smaller heaters are used that equal the wattage of
one heater, the possibility of complete heater failure is almost eliminated.
If
one heater should stick in the closed position, the temperature will raise only
half as fast, giving you a greater chance of catching the problem before it
becomes serious. If one of the heaters sticks in the open position, the other
heater will prevent the temperature from dropping as far or as rapidly.
