My colors are great right now. Among many things I attribute that to is ROWAphos. I think because ROWAphos (or any GFO used properly) pulls out po4 before the bad guys get it, it helps to keep the tank clean and SPS to do well. I always wondered if just cuz you read zero on a high quality po4 kit - you could still have them, just that they're consumed quickly by undersirables. We add po4 with food, ca rx, etc every day.
That said, I am actually going to discontinue its use and try a zeolite program. Cuz if it ain't broken ... you can still tinker. ;-)