Wow, some great information in this thread!
I agree with what Myka, Canadian, and mr.wilson have already said. I specially agree with what Canadian said about the curing methods of live rock... my live rock is still maturing, there is always all kind of detritus and junk coming off my rock (well, the Vanuatu rock at least). There are also a lot of living creatures on this rock, so that may have something to do with it... but, when I take a turkey baster to my rocks you should see the junk that comes off them. If the problem is indeed some nutrient leaching from the rock (very likely), you're in for a battle but it will end eventually. Look at it as cooking rock in a running tank
I think people underestimate the value of cleaning your rock... make sure you give your rocks a good squirt at least once a day, it will help in the long run.