In a message dated 2/23/99 4:01:58 PM, Aquatic-Plants-Owner at actwin_com writes: <<I'm wondering what to do with the middle chamber (of 3) of my Fluval 403. The bottom chamber is full of hexagonal ceramic beads; the top chamber is open cell foam. Any suggestions or comments?>> Why not another chamber full of foam? Lots of us do that ;D Susan