I'm really interested in how you turn this around. The thing that really gets to me is that photo of the sunset monti that you posted above. That photo is so eerily familiar. That is exactly what my encrusting monti's look like when my tank is starting to take a turn for the worse. While all my other corals in the tank look good and are growing, the montiporas are the first to lose their base color and look like crap when something gets out of whack. But then things turn around (like it did with you) and the monti's regain their base color and polyp extension. And the sometime down the road, it happens again. It's weird... This hobby seems so simple when everything is going well and the tank is on "cruise control", but it can seem so complicated (chasing numbers, supplements, trying all kinds of weird stuff, etc.) when trying to troubleshoot these types of issues. You'll figure this out and get through it, and we'll all learn something from this.
You mentioned that you have a hammer coral that is bleaching and retracted. Do you have any LPS or softies, and if so, how do they look? Are you still scraping algae off the glass every couple of days? I may be way off on this, but if you are scraping algae off the glass every few days or if you are growing algae in the sump, wouldn't that indicate that the nutrients are not too low? Or does the algae rip the nutrients out of the water before the corals can use them? Just thinking out loud. I'm following along and hoping for the best.
