I have a 75 gallon setup with a 30 gallon sump/refugium. The display has a 1"-1 and 1/2" sand bed. I'm going to be running a bermuda 5c skimmer (rated up to a 400 gallon). I'm curious as to what you guys think I should put in the refugium? I was think miracle mud but don't know if its worth the $. what about just rubble and chaeto? Any suggestions?