The spa aerator is running to help bring the TA (total alkalinity) down but I think the pH has to be lower for that to be effective. You can search for the posts but I believe somewhere between 6.8 and 7.2 is ideal. Another solution would be a partial drain/refill which may not be a bad solution. You may want to vacuum to waste for a while and just replace the displaced water with fresh.
The aeration does NOT lower T/A. Lowering pH with acid does that. Aeration RAISES pH without raising T/A--the only way to do that. But it all only works when pH is at or below 7.2

pH at 7.2,7.3 is perfectly FINE for chlorine. You can go to 7.5 safely. pH of 6.8 can damage vinyl pools--do NOT go that low! You shouldn't swim in water below 7.0 either.