The Aqua One Glass Aquarium Heater range is a simple but effective aquarium heater suitable for all fish tanks and terrariums.  The built-in thermostat allows you to pre-set the temperature you need so the heater automatically turns on and off through the day and night to maintain a constant temperature.  Fully submersible and guaranteed for 24 months.

Which size?

The general rule of thumb is to have 1W of heating energy per litre of water, so a 100W heater will heat a 100 litre tank.  If your tank is between sizes, choose a larger heater as it won't have to work so hard to keep the temperature up.  If your room is particularly cold, you may also need to go up a size as the heater will have to work harder in a cool room.  If your tank is larger than 300 litres, it can be better to use two smaller heaters to share the work.