Bioballs are best used out of water with water trickling
over them. They do work under water, but do their best
work out of water with water trickling over them.

For reef tank, just use live rock and live sand filtering,
and a protein skimmer.

Wayne Sallee
___________________________
Yeah, I know. But I have this tank with a built-in filter I'm trying to
make use of. It's made like a power filter, in the back right corner of the
tank, except the entire left side is screened for the water to flow in, then
it goes over the first section, and under the last section. Right now I
have it stuffed with bioballs and a powerhead pumping the water through and
back into the tank.

I could use it for an overflow box, but it's only a 20-gal. tank and I don't
really need a sump.

What if I just planted a mangrove in it? Or I could remove the screen,
and critters could hide in it. I'd have to take the tank apart to remove
it.

Cindy