Scrubbing hair algae bleached some SPS

[Stephers]

My tank is 6 years old, but I've been fighting a decently bad hair algae problem for some time. In an effort to get ahead of it, yesterday I tried to remove as much as possible. I took rocks out and scrubbed them and rinsed them in fresh saltwater, but most of my rocks are covered in corals and cannot be removed without breaking said corals. So for those, I just pinched/scrubbed the algae out and siphoned out the algae pieces as I went along. Today I woke up to several of my acros completely bleached while others are perfectly fine. I have a very very large slimer acro which is very very pale now and a PC rainbow which is pretty much completely white alone with another acro. MEanwhile, my bonsai, montis, and several other acros are all unaffected. Most of my lps/softies/anemones appear completely unaffected. I ran some fresh carbon and turned down the lights a tad, but I'm at a loss as to why this happened. I have a microscope and it is absolutely 100% derbesia algae in my tank. I found a couple threads on here documenting similar with no real answer (i.e. https://www.reef2reef.com/threads/removing-gha-causing-sps-bleaching.760784/)
Anyone have any idea why this happened?

 

[fishski13]

I would check your phosphates, I know scrubbing hair algae can cause phosphate spikes.

 

[Stephers]

I would check your phosphates, I know scrubbing hair algae can cause phosphate spikes.

Thanks, but that doesn't appear to be what happened. My phosphates were 0.104 on Thursday, and testing just now they're at 0.086