Can water conditioner, Aquasafe to be specific, go bad? I recently got my aunts old tank set up that she hasnt used in about 5 years and it came with the water conditioner. I opened it and it didn't smell like the one that i had, it was stinky and smelled like fish. Strong fish. I was scared to use it, then I acciedentaly grabbed it and ended up puting it in my new tank water. I didn't catch it till I had gone to put it away. The fish seem fine, I added my own to the tank as soon as I realize it.

I suppose that if it is still before the expiry date then you can use it, although like most things it would be better to use it up within 6 months or so of opening the bottle.

If the smell is very strong, it may be that the it has been exposed to the air or has long gone off, so personally I would dischard it to be on the safe side.

Definately don't use it if it has past the expiry date though. Water conditioners contain safe chemicals (can't remember the name of the main one now) which neutralise chlorine, chloramines and heavy metals. These chemicals will only remain stable and active for a certain period of time, they have a "shelf life" after which the manufacturer won't be able to guarantee that it is effective or safe anymore.

Personally, I think I would probably just buy a fresh bottle

Yeah I did, I was more worried that I had accidentaly put it in my tanks then anything. My fish are fine so Im going with the no harm done. I So threw that away though.

Thank yoU!