Cory writes: <snip>> I was asking about the bare vs tanks with substrate, because I seem to have > had trouble with ammonia buildup in bare tanks. If your ammonia is building up in bare tanks, then you don't have enough biological filtration. Get a bigger sponge, or increase the flow through the existing one. If you are using a power or canister filter, remember that you lose most of your biological filter everytime you wash or replace the pad, bag, screen, or whatever else is in it. These replaceable-media filters depend in part on residual bacteria from the gravel to get them started again after each change. Bob Dixon ------------------------------------------------------------------------- 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"!