I would say get the siamese foxface but they will be eaten by the gars.
You could get a flagtail prochilidus, they do a far better job at cleaning glass than plecos. Or you could go for some nice soft subdued lighting, I believe gars prefere that anyway.
You could also reduce the amount of hours the lights are on for, or just simply get a razor blade and remove all the algae on a regular basis. I believe you can get them on sticks for use in Marine Aquariums.