After watching Kory’s YouTube video on prefilter sponges I ordered from Aquarium Co-op the lg. Sponge to fit on my Emperor 400 Filter. I couldn’t find a sponge that had the right diameter hole for the rectangular intake. It fit perfectly and I couldn’t be happier.
The pre-filters are working great! Holes were a little larger than I thought they would be however just shoved some medium filter in the hole and the filter works great
So far so good, it doesn't clog up like the last sponge I had