In my 120g I use 2 250W 6500k's and an icecap 660 with 4 110w's. 2 50/50 and 2 actinic blue. You can't run 3 MH's in a 120. There's a brace across the center. You'd end up melting it. Right now I've only got a sebae anemone, a pagoda, and an ultra maxima, plus tons of star and button polyps, and loads of shrooms coming back. If you really want an SPS tank, I'd trade in the 250's for 400's. They'll do ok under the 250's but really grow under 400's.