The powerheads won't clear up your water. If you want to clarify your water, you can run carbon in a section of your protein skimmer that water is forced through or buy a canister filter. I wouldn't run the carbon 24/7, every couple weeks for a day or so should do it. You could also try running something called ChemiPure Elite, which will help clarify your water.
But if you do want new powerheads, I use Hydor Koralias. I like them a lot.