Hello and Welcome to R2R! It is amazing that a clown will kill other fish. My clown killed several fish and a shrimp until I realized it was that bugger. I removed him and now life is in the QT. I probably should sell it. Clean up crew as you have should be fine.
Welcome to R2R! If I didn't misread your first post, it seems you only have one grazing algae-eating snail. I would definitely add several more. My favorites are Ceriths and Trochus snails. They will both help with the algae on the glass, but won't clear it, and any on the rock work. The Ceriths will also help, a little, with the sand bed. I'd add probably four or five of each and see where things go.
--edit: also keep an eye on your hermits, they tend to like Cerith and Nassarius shells.