I always have problems with sps when its a new tank. But once a tank matures and have dissolve organics it should be fine. I had 0 nitrates and 0 phosphate in the past and they grow just fine but i have fish. Or it might still be adjusting to your tank. Mint pavona are easier sps. Mine is getting blasted in the middle of 250W Metal Halide 10,000 K in a standard 90 gallon.