In an agressive 125...........How small grain of sand would you use??? Is 2 inches enough or would you go 3 inches??? Is Southdown too small??? Those who already have a set up, what did you use???
Southdown is never to small for saltwater applications, I'd go 3 inches at least on an aggressive tank.
Some might say 1 inch and vaccum it, others might say bare bottom. I just happen to like sand.
Thomas