We've tried to use spent cartridges of Tapwater Purifier and it's a bit tricky to get the right amount of peat into the cartridge because it swells too much and water doesn't go through all that well. The peat causes the pressure inside the cartridge to increase to such an extent that it blows off the tube. If you let it work via gravity, i.e. upside down, it's alright but s-l-o-w. Really really slow. Putting peat into a fluval canister filter works much better. Gabriella ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!