I would start by getting rid of the bio-balls. They'll become a nitrate factory!! If you insist on keeping the wet/dry filter, at least take the bio-balls out of it. You'd be better off going with a large rubbermaide container or the largest tank that will fit in your stand. Those would both be better than the wet/dry filter. Next, I'd add more circulation via more powerheads. You want to look for about 600-1000GPH, NOT counting your sump return. I'd also think about adding more live rock. You mention having a CPR skimmer overflow box, but you don't mention if you actually have a protein skimmer or not. That info would help out. You definitely want a decent skimmer if you want to keep corals. I'd stay away from CPR skimmers. Look at the Remora skimmers. Great Hang On unit for your size of tank. They can also be used in a sump.
With the lighting set up you have, you shouldn't have any problem keeping most soft corals and some or most LPS corals. Boosting your flow will definitely help with both of those as well. As far as SPS goes, If you have rockwork pretty close to your lighting, you may be able to grow Montipora Digitata or Montipora Capricornis if you keep them close to your lights.
