And check your ammonia levels every day, it looks to me as you are now in the process of doing a fish-in-cycle. That means that the waste that your Betta produces will show as ammonia in the water. Until you have established bacteria in the filter that converts the ammonia into nitrItes, and the nitrItes into nitrAtes you will have to keep the ammonia levels as close to 0 as you can by doing daily water changes.
High levels of ammonia are toxic to fish, it burns their gills and can damage their organs. It lowers the fish's immune-system and your fish get sick!
High levels of ammonia are toxic to fish, it burns their gills and can damage their organs. It lowers the fish's immune-system and your fish get sick!