Hi,
Given the information we know from RC, we should at least look at the possibility of the DSB doing something that we didn't intend.
If it was simply an overfeeding problem, then we should have seen this problem since day one. I seemed to recall that Teevee said that his tank has been doing quite well until recently.
One puzzling thing is the refugium...where did all of the macro algae go? The worms are an indication of high nutrient content in the water. I guess we can use them as nutrient export? You can also try to grow Xenia's...good nutrient exports too
One simple test to see if your DSB is okay and running properly is to check for Nitrogen gas. If your DSB is releasing nitrogen gas on a regular basis, then it is working properly and efficiently. If it isn't...umm...either you don't have significant levels of nutrients in your tank or...it is not working properly. In TeeVee's pictures, I do see gas pockets in his sand bed. The question is...are those pockets growing and is the gas being released?
Any who...the solution to the problem is the same as what others have said...export nutrients (skimming, restart refugium, siphon and etc) and feed less. You could use an oxidizer like Chemi-clear to supercharge your skimmer, but I would use it with caution -- especially with sensitive corals.
Good luck!
- Victor.