OKAY....SO you keepers that use (or have used) sponge filters what is YOUR experience as far as powering these vastly underrated filters, I have been using sponge filters for several years,,and am currently debating,is it "better" to use air driven or powerhead driven sponges for BIO.... AND IF YOU LIKE POWERHEADS, how about gph... whats your formula for bio/ mechanichal trade-off... thanks for your time....LEE