Ed, if there are some highlights to that thread you posted, I'd like to read them here. You need a login to access that page.
I understand your points. I dont really think that dumping food into a tank does anything to help corals. It's been discussed in great depth how coral feed on such a microscopic level. It is debated that they cannot even take in the Amino Acids that are sold for corals.
I've been lurking on this thread hoping it goes somewhere. I dont have this problem of lightned corals....anymore.
I dose nothing in my tank other than homemade 2 part for Ca & Alk. I run Rowaphos in a reactor and Carbon also.
There has been a lot of PH talk here. I doubt if that's a magical cure, but I have to say that my tank was at the same low level as the one in question here. 7.8 to 8.1. I've been dosing the baking soda formula for my alk for a long time now. My PH is higher now at 8.3 - 8.5.
I didnt see it here, may have missed it, has anyone mentioned Zeo products. No I've never used them, too pricey for me. I think there is something to it though. Possibly Iron Supplementation. It's well documented that Iron can change the color of corals. I believe it usually Lightens them by forcing the coral to expel zoox. It is said that Rowaphos adds Iron to a system, it is Rust after all. I do run lots of Rowaphos.
I also have a well seasoned Sand Bed. Could be adding just the right amount of food for corals...who knows.
I dosed Vodka for a over a year, now theres a N & P story for you. I bailed out on that one, due to lack of interest from the general public. I didnt want to be the only one on the block getting my tank drunk. I think generally that would be another coral lightening thing.
I think you are either looking at Stability making your coral heathier and darkening on it's own, Stability meaning Everything from Water quality, cleanliness - water chemistry, Ca & Alk - and water flow, lots of it ( I think you have that covered).
Stability - or an addition of chemicals as food or supplementation to coral.
There's my story, I'm here in Monmouth County if you ever want to have a beer and talk about it.
Hef