Thought I might try out Purigen. I have an Aqueon QuietFlow HOB filter. If I wanted to use Purigen: Do I use it WITH my charcoal/floss "insert" or instead of? My floss is still OK (I've been rinsing it) but the charcoal is probably spent. If I somehow fasten the bag of Purigen to the backside of the floss/charcoal cartridge, would that work, or would the water just flow "around" it, since the bag is smaller than the cartridge? If I wanted to use it in place of charcoal, how do I get it to stay in there where the water will be "pushed" through it properly?