Funny you should post this, I was thinking about ordering more of this and giving it another try. I think it may be that I was using the packets in the HOB AC's and not in a canister filter. They got dirty on a weekly basis and had to be re-charged a lot more than every 2 -3 months. I was doing it weekly, rotating between three different packets. I'm about to switch to a canister filter this month so when I get it, I'll try the Purigen again. I generally like all the Seachem products I've used, but cleaning these packs was getting to become another weekly chore. Right now I'm still using the HOT Magnum for polishing every other night. But since I'm feeding less now that the kids are growing up maybe the Purigen will last longer. One thing I'll never forget was that first night I put one in and came down next morning to the cleanest, clearest looking water I've ever seen.