I run 4 T5's over my 40 breeder and am having great success with it. I don't keep sps on the sand but they all grow. Now that your are on the verge of changing bulbs you are going to start seeing some success. The thing about ATI bulb combos like you are considering peak at the spectrums that REALLY promote coral growth and color. If you are interested in staying with T5's and don't wanna fork over ATI module cash, google LET retrofit fixtures. Same quality reflectors, same quality ballasts, add your own fans and bam, 4 T5 SPS system with these, 6 would be boss though.