he means the filter sponge in the box on your drain pipe...not only will it collect garbage and poop creating a nitrate problem...it will also greatly restrict the flow to your sump...combined with a HOB overflow you are asking for a flood...
Oh, misunderstood. The filter on the pump is temporary. Just using it to clean debries out of water from the build, dog hair, floaters etc. It will be removed. Also the design of the overflow and the 2 holes I drilled into the return line below the water will prevent any flood. If the pump quits pumping the overflow will stop flowing as the water line is 1/4" above the skimmer of the the overflow. Siphon will break when it reaches that point. If the overflow plugs or quits the pump will pump until the last compartment runs dry. I may add a float switch to kill the pump so it won't burn up.