I have a 5 gallon non-planted tank with 3 little African Dwarf frogs. I'm currently using a small Cascade HOB (Cascade 20, I think) filter with a sponge pre-filter to keep little legs and feet safe. However, I'm getting a ton of particulate matter floating around in the tank, which obviously isn't getting past the sponge. Can anyone suggest a better method of protecting froggies from the intake, that will still allow some mechanical filtration to happen?