Hi, I also use the fluval, like all cannisters and sumps they can become giant Nitrate factories, In my opinion the best bio controllers are live sand and live rock the cannisters will just build up as will sumps . Now we only use 303 and a 404 for carbon and poly fiber just for the big floating particals.
and for the sand you have you need to seed it with some live sand or some of the sites sell kits to do this , I would myself get a bag of live sand or if you know someone with some see if you could get a cup or two, cya
[ April 24, 2001: Message edited by: fixitdude2001 ]