It's crossed my mind.
I have 12 5' tubes over my tank. 5 Blue+, 5 Aqua blue, 1 Actinic and 1 Pro color. I would imagine that's a good deal of PAR down the centerline.
I tested P04 and am hard pressed to even get a reading on my Elos test kit. I like to think I run a reasonably clean tank.... couple small feeds a day instead of 1 large one, high flow, wet skimming, hydrovac sand once a week, etc,.... but you'd think I could at least ping somewhere on the Elos scale.
My orange montis only started lightening up the last 3 or 4 weeks. It was right after the 2nd round of meds that they bleached almost overnight. However they still have some orange tint so I'm leaving them be for now. Several other acro colonies that were doing a good job of holding their color went almost overnight after adding the meds as well.
The rest of my losses I think were a combination of water quality and then the bounce from low light that came from the med tinted water, followed by the sudden shock of clear water when I removed the meds and turned the UV back on. Several colonies were already half bleached and those went quickly. Yet others, bleached on the tops or the side facing the light, but are just fine around the underside where the light was less intense.
Surprisingly, and when was the last time you heard this one.... the more rare or expensive the better they faired. My superman monti has gone a little brown, but is otherwise intact. One sunrise monti up high died outright, but the one lower down is mostly OK.
Actually, it sounds worse than it really is. If I count all the corals I've purchased since January it's probably only a 15% to 20% loss.
All my LPS are fine
All my gorgonians never missed a step. They remained open a good majority of the time. Go figure!
Zoos & mushrooms all fine except for 1 multi-colored Ricordia which is still trying to make up it's mind.
Brett
