SPS problems

100% you say? That's an awful lot, even coming from 400W MH. Light shock (photo shock) is now a suspect, causing bleaching.

 

What leads me to believe this is an rtn event is that it happened in 24 hours. If it had bleached, wouldnt the process have taken longer? I think the black stuff may have just been dead tissue falling off the coral, since it appeared and then was blown away by the powerheads. It actually did not look like the polyps were expelling the stuff. I suspect either a lighting or flow issue has caused this, like you guys have mentioned, because all my lps and softies still look very healthy.

 

Yes, they are on at 100% intensity but spend most of the day ramping up and then ramping back down. The time spent at 100% is very minimal. They run from 9 am to 8 pm and sit about six inches above my 30 inch deep tank. If anything, i had thought this would not be enough to keep sps but do you guys think this is too much?

 

Also some more info:
I use all API test kits. I had my phosphate checked at my LFS about one month ago and it came out to .03. Its been undetectable ever since, so I assume its still about that. I normally do weekly water changes of 15-20 gallons but have not done one lately because levels are good. The montipora still has some small black fuzz that I'm guessing is cyanobacteria. I have seen a bit of it on my lr ever since I switched from t5 to radions, which are on for 4 hours longer. I made the switch long before these SPS were added. As for flow, my powerheads are pointed indirectly at the sps with my two return pumps (700 and 1100 gph, but feel like much more) pointed across the length of the tank. I still havent seen any sign of pests. I have removed the dead acro and dont see anything.
Thanks for all the input. Any further opinions are appreciated.

 

Here's a bit more quality info on RTN:

That doesn't address flow however. IME, RTN can be caused by lack of flow as well. In a 150g tank, I'd like to see 7500gph or more (even up to double that) for SPS. IMO, your return pumps don't count for much.

 

Im looking at getting the Hydor Koralia 8 Magnum (3250 gph) and a couple of rotating deflectors to randomize the flow. That will give me 62x turnover so I'll see how that works and add if necessary. Thanks man for your help.