Foam bricks, cut to size and shove in filter. I dont waste money buying new pads anymore, just rinse out the foam pieces once a month and use a filterbag for the carbon. I used a peice of pantyhose, filled it with carbon then tied off the end, it sits in the filters with the foam blocks. Insted of 1" of foam pad to trap debris, you have 4" of pad. Pm me me if you want more details on the money saving filter improvments.