Well, as I said, I'm not sure where you heard it...but the Whisper box that I have says to replace monthly or when water no longer continues to flow through the filter bag. Now, maybe it's just me, but I consider a month to be about 4 weeks.........0morrokh said:Hmmm, wierd. That's not what I've ever heard. ??? Maybe the reason it doesn't last so long in aquariums (or maybe it does...) is because there is so much more to soak up and it becomes "full" very quickly. Right now I'm cycling my tank and the carbon isn't more than a week or two old, but it certainly isn't adsorbing the odors from all the rotting flakes.
It's not just the odors.....See my post above......atmmachine816 said:Well I don't use carbon anymore and I have no odor so it's doesn't absorb odor in a cycled tank, but interesting point brought up.