That mushroom garden looks really nice ... A warning about the clam (not that you haven't heard it before), but it will not live long-term at the bottom of your tank under PC lights. If you check out the clam forum, there is not a single person who has been able to keep a medium size clam alive long-term with pcs (especially at the bottom). When it dies, it will really pollute your tank. Just a warning, I don't mean to sound like a jerk.