There is a good youtube video on bulk reef supply about dry rock, curing it, and then cycling it. I just received some dry rock and I am letting it sit in salt water for two weeks with a heater and circulation, and then I am going to put it in one of my tanks to cycle. I am on day 10 of the two week curing process and the water the rock is in does have a faint yellow color to it. I've never used dry rock before, but the video said to cure it for two weeks in a seperate tank or bucket with no light, and then put it in your tank to cycle.