All the aragonite Petco gets up here is the 1.5 mm and larger (Arag-alive) stuff.
Be careful of Oceans Marine sand, they like to pawn off silica sand as natural ocean sand and the like.
All the Carib-Sea sand comes from Bermuda so it ought to be readily available on the east coast for no more than it sells for at Marine Depot on the west coast.
I prefer about 70 percent 0.1 to 1.0 mm oolitic and 30 percent 0.5 to 1.5 mm oolitic with a top dressing of GARF grunge, which is a mixture of dust, sand, live rock fragments, and lots of bacteria and critters. I would go finer but not with heavy circulation. In sumps or other remote DSB applications I use all 0.1 to 1.0 , mm or 0.1 to 0.5 mm when I can get it. If all I can get is 1.5 mm or larger I cheat and take it to the university and use the crushers used for core crushing. It will only readily crush down to 0.5 mm though, with about 10 percent down to 0.1 to 0.5 mm.