The 90 is still pretty small for a CL, especially with just LPS corals. One powerhead like a vortech and a half decent return pump would be good. For an LPS tank I wouldn't aim for more than a total of 10x turnover or about 1000gph. Have you considered going the simple route and using a larger return pump like a dart? You could run a herbie overflow to keep noise and bubbles down and eliminate the need for powerheads or a closed loop. It's be much simpler and cleaner. I've setup a few 90s like this and they've all done well for LPS and even some SPS.
Don't under estimate the importance of simplicity.
