I will soon be setting up a 27 G frag tank but for right now with my first paly frag I've set up my JBJ Picotope that was just sitting in the garage. Just the basics, heater, little powerhead, aquaclear 50, stock light, and egg crate.
Have one in my main tank. I love him lol. I'll be switching to a 27 gallon shortly though. And my problem with one in a z/p frag tank is they lay on and close up the polyps. Adorable fish though lol