Does anybody else out there use this stuff? I am using it on two of my tanks now (I find it difficult to fit in to my nano tank filter) and am mightily impressed with the water clarity it gives. All my tanks had what I presumed to be crystal clear water, but Purigen takes the clarity a notch higher. It is most noticeable in my Iwagumi which is basically a lot of water column inside an opti white high clarity glass 60cm tank. The only downside is that you need to open up your filter every three weeks or so to regenerate the stuff overnight, and then open it up again to put the Purigen back in the following day. What I do is keep a spare bag of Purigen, so when I take out an exhausted bag the standby goes straight in. The exhausted one is then regenerated and left as standby for the next filetr opening. it is still a bit of a pain, but it minimises the number of times you have to open up your filter. When I do water changes, the water I take out is clearer than the tap water going in. Dave.