I just posted something regarding this. I have fed aminos, coral food etc while keeping PO4 at .03-.05 ppm (Hanna ULR). The SPS color and PE hasn't been great. I recently was out of town for a week and set up an auto feeder to dump a mixture of pellets and flake in the water twice a day. When I returned my sand bed was very colorful and the glass was filthy. When I peered through the filth the SPS color and PE was dramatically improved. Alk consumption had spiked. I had no idea I could see such a quick, positive reaction in my SPS. For my tank it seems dirtier water in general is better. The pellets are that Neptune stuff coated in coral food, perhaps that's magic? I can deal with the extra cleaning duty if this is the result.