I have about a 1 inch sand bed and in spots with low flow have put some sugar sized sand. I try to used rock to create a area that has the sugar sized sand and I put it over the bigger sand. I also have about a 1 inch sand bed in my sump.

I use the one inch to allow for a natural look and to try to prevent much anaerobic stuff going on that you might find in a deeper bed. I use to keep deep beds but after turning it over and killing fish I stopped that.

Having sand will allow you to keep other species of things and if your sand bed is big enough then a sand sifting star will keep it turned up. You might be able to support one in a 115 if your rock base does not take up a lot of the tank. I have kept them in smaller reefs but I think they struggle to find enough to eat.

Mike