Temperature Decrease

[rdd1952]

It says on it 20W (don't know if that's right, sounds it) the tank is 54 litres. The heater came with the tank so it should be the right heater.

That is the problem. A 20W is really only good for a small (less than 5 gallon) tank. Your tank is in the neighborhood af 14 gallon so you need at least 50 watts and probably 100. As Inchworm said, 5W per gallon would be about 70W.

 

[Bre_B]

...I hope thats not my problem, too! That woudl stink, all this time wondering what was wrong... oh well, im getting a new heater soon anyway, I shall just steal that advice