Hi - I'm going to be getting a HOB Refugium from CPR....the medium sized Aquafuge. I can't tell from the spec's, but does anyone know the max depth of a sand bed you can put in there? I will also be putting some chaeto and maybe some LR rubble in there to help with nitrates. Also, for people that have either this type of fuge or sump-based ones....do you put any wildlife in there? Particularly any snails, crabs, etc.? Or do you leave it with just what comes on the rocks. Thanks.