Only reason I can see why you'd want bioballs in the overflow box itself would be to dampen noise by breaking up the flow of water some. Personally, I have some sections of eggcrate stacked in the outside-the-tank section of the overflow box. 4 or 5 layers stacked end up being about 3-4" high and they seem to do an even better job of breaking up the water flow than bioballs do. IME, bioballs tend to be almost too massive and end up slowing the water down, while the eggcrate just disrupts the water enough to squelch some of the noise.
Also, is your tank a reef or a FO? If it's a reef (or even a FOWLR), you really don't need the bioballs. If it's a full-reef, they even become a hindrance in that they'll become a nitrate factory. Don't know if you knew that or not, but thought I'd toss it in just in case.
The overflow box would probably serve better as a prefilter by putting a sponge in it that the water must pass thru. This prevents unwanted debris from reaching your wet/dry or sump.
The overflow box would probably serve better as a prefilter by putting a sponge in it that the water must pass thru. This prevents unwanted debris from reaching your wet/dry or sump.
Yes, that's true. I was thinking of it in terms of my sump, which is set up as a refugium rather than a wet/dry. If you're running a wet/dry, you probably should have a sponge of some sort in the overflow. You just have to make sure to clean it often or it'll clog and really slow your flow down. I've heard of tanks overflowing when the wet/dry is pumped dry while waiting for the water to pass a clogged overflow prefilter.
