It doesn't matter if you run only 6500k bulbs if your phosphates/water quality is good.
Like I said before you need GFO or more of it more often. New bulbs will help but there is a water issue at hand also if its as bad as you make it sound.
I had the same thing happen, I dropped my GE6500 bulb for an actinic, didn't help much, these are 4 month old bulbs at the time.
More blue, less red spectrum, less hours, new bulbs, more GFO should slowly help. Removing a red spectrum bulb will not help much unless you take care the underlining water issue.
I understand your point, Mike. I found it strange that as soon as I put the 6000k mid day in, brownish HA showed up. I have not run GFO is quite some time and the algae issue is very minor. As all of us know, it's not well liked regardless of its severity. Also, the algae is in recession....just not happening as quickly as I would like. The reason I came to the lamps as a partial conclusion is that I run biopellets, have a moderate bioload, and skim heavily. In fact, the water became so clean that SPS began to suffer a bit however that's been resolved via reduced flow through the pellet reactor.
I appreciate your opinion and will continue to look at water quality. Strangely, nitrates and phosphates are nearly nonexistent. In any case, SPS growth has been good recently.