Sps

[Snappy]

I would venture to say yes you can do quite well with that lighting depending on the coral......It depends on the types of sps you want to keep. There are so many variables.
I used to have 175W mh and had some pretty reasonable results, so for the most part you should be fine. I would however warn you that if you start growing sps under 175's an upgrade is eventually inevitable as you will start to want the harder to keep species to get more colour. Well maybe that was just me.

[Mik_101]

Ha ha i bet that will happen 110%

[michika]

I'd say your probably okay to start with something harder and move on up gradually. I keep my SPS under 175w in an 18" deep tank, and they are doing quite well. I admit it takes a bit longer for color to recover, but so far I'm pleased with my 175w.

[DanG]

just don't go with too high of a k bulb, try to stay arount 10,000k as they will have a higher par output than a 20,000k bulb. get some decent actinic bulbs and you should be good. 39w leads me to believe they're T5's and if so, URI and ATI both make great HO T5 actinic bulbs.