thanks guys sorry for the lag on the response. i broke my ankle.....so im no doing anything at the moment, but my idea is to remove my gravel from the 55 and do a mix of crushed coral and arogonite sand (however you spell it) i need recommendations on how to do it without endangering the fish with the multiple stacked rocks and such.....and then specific names of simple fish to keep in such a setup? thanks ahead of time