Yesterday I added two new dwarf puffers to a ten gallon tank yesterday that has been set at 78 degrees. I hadn't noticed this before, but I think my lights are heating my water. When the lights are on, the heat is about 83 degrees. When the lights are off, the temp drops to about 78 which is what the heater is set for. I have two thermometers and they both say different things.
What should I do?
The only things I can think of to do are:
1. Put the DP's in my 29 gallon community while I fiddle with the heater and lights and work out a way to make it all stable (don't know how they'll do with the other fish, they are friendly with each other anyway)
2. Keep the lights off and buy a new hood that is further away from the tank so it doesn't heat the water (I don't even know for sure if that's what's going on, I'm just guessing it's the lights that making the water so darn hot) (translation...spend even more money)
3. Set the heater to 84 degrees and let it remain there, and risk that the lights will raise the temp yet even higher.
The don't seem to mind, but time will tell. I don't know them well enough to see "stress" in them.