i have taken filter baskets out full of media and left them in a bucket of water, no filter, no heater, no oxygen, for more than a few weeks and the bacteria had grown everywhere inside of the bucket.water was very clean. i thought they would of died. so left them in there and has multiplied even more since i last checked it last week. :-? ive never had problems with bacteria dying, filter changes, fish dying because of it etc.