In my sump, I have a sponge filter just in front of the pump in the water path to my return pump. All water going to the pump must pass through this filter This one seems to catch bits of macro algae returning from the fuge as well as other “mudd”. Also I run a course sponge pre filter on the overflow from the tank along with a fine filter in the sump on the overflow outlet. All (3) of these get cleaned every weekend. Before installing the fine filter on the overflow outlet, I would have to throttle the discharge of the 800 gph pump, (to decrease flow rate) so that it would run a week with out sucking a bit of air (because all water flowing to the pump must pass through the sponge filter, the water level around the pump would get low enough that a vortex forms and the pump begins blasting bubbles into the tank). With the extra filter, I have gone 8 days between maintenance activities with out any air issues.