I have a recently-vacated 5gallon tank that I hope to put a
betta in soon, but I've noticed the 25w heater I put in there just isn't doing its job. I replaced it recently for the same reason, and am sure the original heater did work for a while at least.
Seriously, it's set to about 30C - hotter than I need - but the thermometer doesn't get much above 20C. The chart on the side of the box says 25w is the right size for a 5g tank, but should I go for a bigger one?
Also, is it possibly because of the cold water in the tank that the snail I bought hasn't budged an inch, or have I just been sold a dead snail?