First thing I would suggest is go to a plastic shop and order a 4'x8' sheet of black pvc. 1/4" should be fine. Cut it to the size you want and drill holes in it for your frag plugs. It is much easier for snails to keep it clean. Yes it cost more but will be worht it in the long run.
in my frag tank i have a yellow wrasse to eat flatworms and nudis (just in case), a scribbled rabbitfish for algae and some trochus snails for film. also have a sally lightfoot and a few nassarius to eat any uneaten food.
thanks Mark-I was thinking Scopas or some type of Zebrasoma-the chevron was a lazy sucker-I thought he would be good=nope -he's working harder in the display now though-go figure-
with my display connected to the frag tanks-which sea hare would be good if any?
I use Cerith snails. My frag are crowded together pretty tightly and they can get in the cracks. Also if they fall onto a coral they seem to be able to right themselves better than astreas.