I just aquired two large tangs (both 6"- 7") from a friend who was downsizing his tank. They are now in my 110 gal (25 gal refugium) with 2 - 3" angels, a medium flame hawk, 1 - 4" hippo, a medium clown, and lots of soft corals and live rock. For the past three years I've just done a 10%...