My tank is a 1.5-2 gallon fish bowl of stagnant water (ut oh!)
I change 90% of the water every week or week and a half.
Due to the small size of the tank and lack of temperature indicator strip I have not put a heater in, even though I do own one. The temperature is controlled by the ambient temperature and the tank light. With the light on around 12 hours a day the temperature is around 75-78 F which probably a little too cold for bettas. When i turn the light off to conserve energy and not boil the water and bake the fish I'm sure the temperature drops a little.
The water is not treated with anything (eek!) I simply use tap water and let it sit out over night before introducing it to the tank so that SOME of the chemicals from the tap water can evaporate.
There is nothing else in the tank with him. He is not bubble nesting. I find that if I leave the light on 24 hours a day he bubble nests but I'm worried about bacteria growth at higher temperatures in the stagnant unfiltered water.
Thanks for the replies thus far...