Filter media for sump/fry in sump

[Willo]

Hey all - just wondering what materials people use as mechanical filtration in their sumps? I currently have 4 baffles. The water comes in, where i have some marine pure balls, water flows through course sponge material (maybe not coarse enough as it blocks within a week or so). Water then goes through a section of matrix then trickles over bio-balls before being returned to tank.

I used to have filter wool (really fine) that went before the coarse sponge but I found within a day or two this was clogged up, and the water was overflowing the first baffle and going straight to the bio balls. I am going to try a few different products on the market to find an efficient way of filtering out the crap, including a filter sock, but I'd welcome others design choices.

Also, I have discovered half a dozen bristlenose (i think) fry in my sump. I am running a display tank, and don't really want to breed - I'm guessing the fry have a better chance in the sump than in the tank - can anyone see an issue with this choice? I don't want to be cruel, but pretty sure my GT, Jewels etc will make light work of the little guys. I still don't know how they got in the sump though... rough ride, that's for sure.

Cheers,

Diz