I run a filter pad on a tray. The water drains into a small drain chamber in the sump. The water flows up and over a ledge, and flows onto a filter pad. I cut the filter pads from a giant roll that last about a year, buy it on Amazon. I replace the pad about every week. The pad I cut is 2" x 8". I sized the tray section to allow a 4" x 8" pad if I wanted too. Below pic is the 4" x 8" pad, but now I cut smaller pads and replace more often.