I've recently tackeled an aquarium at a local school. The LFS
that was taking care of it abandoned them and left the tank in shambles.
It is a 75g tank drilled with overflow and a 20L sump.
My question is, there are no partitions in the sump, its just a tank. I put some LR
rubble in there, but i need to find a way to improve their filtration. Can anyone give me some ideas on how to improve their filtration in this sump with minimal costs?