Ok cool, so lighting is good, but what intensity do you have the Kessil up to? Also, what is your color balance set to?
Yeah, MB7 is pretty good actually, but you don't need MB7 on a continual basis, just to help your tank get going. Ultimately, the bacteria in a bottle will help in the battle against nitrates, but not THAT well.. I haven't ever used nopox, so can't help with dosing of that, but I would think that nopox should be dosed every day. How long ago did you start the nopox? Can you test for phosphates? That would tell a lot as well.
Man, sorry to be so long-winded, but it really helps. I am really of the opinion that the issue with the mushroom is that your light is too bright which is making some corals bleach, or at least reducing their color.
Don't worry about the other parameters, but look up Redfield Ratio to understand why you need phosphates in order to reduce nitrates.
So a coral losing its' coloration, bleaching, even just washed out, is a big sign that the coral isn't happy with their zooxanthellae and that they are being kicked out of the host coral. Try dialing the intensity back a bit, and try to get the mushroom into some shade to see how it helps.. Could also be that your water is too nitrate and phosphate free to support life, but in your case, that can be ruled out...
Make sure you get a phosphate test kit from your LFS, and tell 'em you want it free, since they made money on your for the last few months...