i have the 19" model hanging on my tank, i really like it, I filled the bottom up to the edge of the lowest baffle with live sand, as well as caulerpa. i also dropped some pieces of 1/4" pvc about 3 inches long each in there. they give a place for the pods to hide and breed and boy are they good at that!!! i got a ton of them. that was a little trick my LFS told me to do to increase the pod population. there are literally 1000's of them in there now, and what you can do is every so often is reach in there, pick a piece of pipe up closing off the ends and then knock them out into the main tank for a nice feast for your fish
another good thing about this fuge is the pump pumps the water in and gravity fed out, that way your pods dont get chopped up when they float out into the tank on their own
