Ugh...it harkens me back to your thread a few weeks ago. Hopefully I'm not in for a ride like that.

It seems to have happened to a lot of people who really had their junk together. Way too many examples to make me feel comfortable about the situation I'm in. The vast majority of the threads that did not find an *immediate* problem (alk, temp, mag, etc) never found a specific cause for their ails. Most of them just experienced a long slow decline across the board. I've never been in a situation like the one I'm in now, that's for sure. Ever since I began keeping SPS I've been wondering what was so difficult about them. Good lighting, good flow, good parameters, etc...cover your bases, wait for them to wake up, and they grow like weeds. I still have high hopes that everything is going to bounce back but I wince a little when I put it into words.
I think it started in the last tank after I got the flame angel. I never saw him picking on the digi but the excellent PE totally disappeared immediately after I got him. The lack of PE never really concerned me as long as it continued to grow. That specific coral was the one that was out of the water for the longest span during the re-scape and it was the first to go. The double whammy so to speak.
I've been watching the flame very closely the last few days while standing in the far corner of the room. He is picking a touch here and there when I'm not near the tank but it doesn't seem like he has the intent of taking a meal from anything. I fail to believe he is causing the problem.
Coral Status:
* Major declines: So far major declines have been limited to the digis.
* Minor declines: Half of my acros. Weak PE and a few tips here and there in my Chips, Green Slimer, Sky Blue mille, Pink Mille, cali tort. My 20K Lokani frag would go into this group too but I haven't seen any STN yet - it just doesn't look quite right.
* No growth with decent/weak color: The monti caps have stopped growing. Purple efflo falls into this group as well.
* No growth with good color: My pink hyacinthus isn't growing but it's showing good colors and no signs of stress. If I weren't having these other wierd problems I would be breaking off tips with the expectation of waking it back up.
* Good growth and color: Cream/green/blue efflo is growing like a bean sprout. Magenta/blue mille has just started growing again too (just woke back up over the weekend). The hydnophora looks good as well. The LPS all look good. The poccis, blue slimer, sarcophyton, and a handful of frags I've yet to place also appear to be doing great.
So far my response has been:
* Changes: to increase the flow, keep my hands out of the tank, and up the GAC from ~1 cup to ~2. Do more water changes. Stop VSV until things have improved back to where everything is clearly healthy. Upping my MH duration back up to where it was prior to the move (I cut it back to two hours/day for the first week and have been adding roughly and hour per week ever since the move).
* Non Changes: Skimming somewhat wet. Continue tumbling 3 tablespoons of GFO. Ca reactor and kalk. Maintain all testable NSW parameters. Temp 79 to 82 per day. Continue heavy feeding.
Any ideas? Someone brought up the idea of adding ammonia and nitrites testing to my regimen.