When you're trying to keep the pH unusually high you will lower it by aerating too much - just the opposite of how you can raise pH by aerating saltwater with low pH.
Messing with pH sucks, and this is one of the few times I suggest a person does mess with it. Having the fish out of the tank just means less risk to them, but don't for any reason ever move outside fish into your broodstock systems. This treatment can be done with the fish in the tank, just be diligent with your pH testing and watch the fish for signs of oxygen deprivation - especially during the black out period.