When I went reef on my 55, I got a T5 VHO fixture (Nova extreme Pro 324W) and started running it from 6am (so I could see it before I went to work) until 10pm. Turned out to be way too much light, and I had way too much algae. I now have my lights on from about 11am to 9pm and it seems to work pretty well. I would suggest maybe starting with a 12 hour cycle for awhile then see how the tank does. What's the wattage on your PC lights? got enough for a reef setup?