Eau, help, how do i lower temp without killing the fish?

[Marne]

I bought a new heater which we put in the tank yesterday, got up this morning and it seems that the heater has not cut out when it reached temp so water was very hot. Changed 30% of the water, switched heater off but its still around 28 (should be 22-24). Do i just let it cool down slowlly? do i move the fish to the big tank or will the shock kill them. I wouldn't be suprised if the fish die as it was very hot, at the moment they seem ok. Is there anything else i can do? (other than cross my fingers that they are ok).

Warm water holds less oxygen so if you've got a spare air pump and bubble stone then that will help, or maybe turn the flow up on the filter if you can. It should cool naturally if you leave the light off and leave the lid up. You could also give it a stir every once in a while but 28c isn't that high so shouldn't kill them.

What makes you think it should be 22-24? That's on the cool side for guppies and mollies, they actually prefer higher temps than many tropical fish. 22 would be a bit cool for them.

I usually set the heater on 22, it seems to make the water slightly warmer than that ( around 44 ) not sure if it's because the heater is too powerful for the tank? Also the tank is near a radiator which seems to raise the temp a bit. Temp this morning must have been up to 35 or more. What temp is best for pregnant guppies?

Its on 26 now even though the heater is set at 22. This should be ok?