Originally Posted by willm
I am aware that bettas are tropical fish and need water that's above room temperature.
I have a halogen light over his tank that heats it somewhat, though obviously a heater would be a much better and more reliable option... but as you said the bowl is too small to put a heater in.
Does water conditioner really take days to work?
The letting it sit for a day or two suggestion is to allow the replacement water to reach room temperature (close to the temp of your main tank) so you don't have to rely on guesswork by placing your fingers underneath a running faucet.
Temperature fluctuation and water quality are the two primary causes for a decline in a betta's health.