Well I figure I'll put this review up on purigen since there's lots of questions going around about it and how it works. I've been using this stuff now in my filters for 7 months and it does an excellent job of clearing my water. It also does an amazing job of pulling out tannins in water that driftwood will Leach out. It will not pull meds out of water or fertilizers if your running it in a planted aquarium. And it's rechargeable so you don't have to keep buying it.I think it's the best stuff out now in my opinion. It's a synthetic product I believe and it has had no adverse effect on my fish whatsoever. I've also been told it's good for reducing nitrates. Here's a few shots of my tank lengthwise so you can see for yourself. It's a 125g so it's 6 feet long. As we all know when you look at your tank lengthwise the water will have a cloudy appearance to it. So check not the pics and judge for yourselves.