I was using a 50W heater in a 5.5g tank and it was ok for my betta during the autumn period when the room temperature was about 76. During the winter time when the air temperature of the room decreased to a value of about 67 or 68 I have notice that at the bottom of the tank water was much colder (73) than at the surface (79) while the heater was adjusted for 79 and no matter in which position it was, vertical or horizontal. What should I do? Should I buy a small filter in order to allow the water to flow? Or maybe an air pump? I am very confused.
I don't want to create a too strong flow for my betta. I know that warm water goes to the top, but isn't it any solution to this problem without using a filter or something like that?
I'll ruin every bubble nest this way...
This tank was used for a betta that developed dropsy (I think it was caused by these extreme temperature fluctuations
), I sanitized it a few days ago and now I am planning to move another betta in it and I want him to be happy and healthy. What should I do?