Foxface!
My tank didn't really have an algae problem so to speak, but the rocks did have places of a deep red wiry algae that looked like enkamat. After a couple of weeks after adding a small foxface, the algae is completely gone. I just added the foxface from a Live Aquaria - Diver's Den visit and they had many on hand at about 2-3 inches. My fish is doing extremely well and has a nice full body, healthy appetite and a mild temperament.
I would imagine a small foxface would really keep your frags clean as their snout can get into very tight spaces.
Just monitor their growth for your tank size.
The kole tangs that I have owned didn't really eat the algae that was already present, but they kiss the rocks and glass to help prevent more algae from growing.
-JASON