I use the Tetra Aquasafe only to start a new tank. I used to use it for water changes but it completely messed up 2 of our tanks. Sent them back into cycles every time I did a water change and treated the new water with that crap. We lost all of our first group of bettas and most of the guys in our 55. I'd be wary of any product that says it has bacteria in it. From research I've done and from my LFS
those products aren't all that great. The bacteria in them need nutrients and oxygen to survive and to make it worth while for your tank. After bottling, shipping, stocking etc not that many of the lil guys are still alive. So when you add that to a tank you're adding mainly dead bacteria. That will keep slapping your tank back into cycles. My suggestion, don't use it except for setting up a brand new tank. Use Prime to condition the new water, some people perfer NovAqua, but the point is, don't use a bacteria suppliment. It's not worth losing fish over.