Based on the last 2.5 years of my usage, T5 can't do better then 250-500 PAR at 6-12" depths. I have never been able to get my SPS to grow (atleast at a good rate) at depths over 15". I can grow everything else at the bottom though, but not SPS. I also have a hard time getting Blue corals in particular to have colored polyps, they tend to go brown on me very fast, as do many others... even at the 500 PAR zone. I have 25,000 gph surges in my 240G SPS reef and no nitrates/phosphates, so it has to be lighting preventing me from getting colored polyps. coral flesh is colored though, just not the polyps.