Originally Posted by
renogaw
http:///forum/post/3174497
by the way... you should NOT have gravel in your salt system.
It's actually not "gravel" per se. Its a sand and crushed stone mix. I actually ran it through a strainer and have VERY fine sand in the fuge, but I left it a bit more coarse in the DT. All my sand sifters don't seem to mind. My next tank will have only real sand, but this tank was originally not supposed to be saltwater, it was designed for some african shell-dwellers
Also, the red thing in the picture is hard and almost feels plastic-like.