I am going to be filling my 90 gallon tank that I have been building for the past 5 months and was wondering how big of a sand bed I should have. I plan on having a normal reef tank I guess you would say. I have a 20GL long tank for my sump and a 10 gallon refugium. I am guessing I would want like 2" of sand but not sure. and how much sand that would be I have no clue. I am going to get mostly live sand if I can. Any ideas?