I was told that bioballs wouldn't be effective in eheims and aquaclears by the manager of my lfs. He said its not the same as when they are used w/ the trickle down method of a wet/dry filter. I use ac110 on my 125s as extra filtration w/ the sponge block and a big bag of chemi pure, works well 4 me.
From DJ/MC Decker