Hi folks, I'm an old school T5 kind of gal, so when I started my new 300g system, I brought my T5s with me. I use ATI bulbs - 4 blue plus, 2 actinic, 1 purple plus, and one white. I have the actinics running from 7AM to 10PM, and the rest of the lights running from 11AM - 10PM. Unfortunately, I'm not having great growth in my SPS corals. They seem to be bleaching out (or receding?) - especially at the tips. Some have great polyp extension, while others show little to none. My parameters are great, with the exception of Po4 - it is currently sitting at .07, so I'm really wondering if it's the lighting. I do carbon dose to keep the N03 at a minimum, however (I have lots of fish). My alk is 8.17, mag 1300, calc 420. I use the balling method to keep my parameters stable. My aquarium is 30" high and my lights are sitting about 8" above. My rock work tops out about halfway up the aquarium, leaving a 1-1.5 ft of space between it and the top of my aquarium. Essentially, most of my SPS corals are approx. 23" from the ATI T5 fixture. Any suggestions??