Or you know, you could still do the automation and run at the TA recommended here at TFP of 60-80 (60 likely good in your situation) and have the best of both worlds: automation and not needing to refill the MA reservoir every week. But to each their own. Maintaining the TA at 90 and then blaming the your aeration ALONE is incorrect.
Well I guess it was inevitable this thread would get sidetracked with a "what's causing this?" as opposed to my question at hand. I was just hoping it wouldn't get derailed so quick. Don't get me wrong. I do appreciate any advice. But I just try to keep the topics appropriate to the sections they are posted in. I have spent much time season after season in the other sections studying up on why my pH spikes. And have come to the conclusion it's primarily my SWG (Aeration from spa to a lesser extent despite you saying I blamed that ALONE)
So here goes another discussion in the wrong section:
Last year I once and for all wanted to see how large an impact the SWG was on Spiking pH levels. So in late June after pool was open and running for a while and the nasty pollen had settled down I did my own experiment. First thing first, I went to Costco and bought a dozen cases of Bleach. (3 per - so a total of 36 Gallons).
Next I brought down my pH to 7.2 using MA which I buy from Lowes. Then I completely turned off the SWG. I also drastically reduced the amount of time my spa would spillover during the day. (I had to run it somewhat otherwise the spa water would never have been circulated).
For the next 2 weeks I chlorinated using bleach and only bleach. Every night I would come home from work and add another gallon. Sometimes 2. Sometimes at even other points during the day depending on heat and sun. I was keeping the Cl High. I wasn't taking a chance of getting a bloom during this experiment.
Test pH every night when I would get home before I would add more bleach. Night One - 7.2, night Two - 7.2, night Three - 7.2, etc. You get the point. At the end of 10 days I was reading 7.6. Cool. No need to keep up this nonsense when I have an expensive system I wasn't using. So that Sat morning I put the SWG back on it's normal setting. Turned the Spa spillover to operate through the duration of the pump cycle and stopped adding bleach.... In other words - Everything back to "Normal"
Monday night - come home from work - pH > 8.4 (purple darker than highest mark on the vial).
Now I never thought of a TA reading of 90 to be overly high, unacceptable or a level that causes excessive pH bounce. I am curious as to why you say 60 "in my situation" is better? Is that because I am running a SWG? I guess I am confused as to what makes my situation unique. But I am certainly willing to listen.
But none of this changes the fact that I am going to still experience pH bounce with the use of a SWG. Thereby requiring frequent addition of a "pH down". I have no problem controlling it with frequent doses of MA, I just prefer a system where I don't have to handle acid every other day. Which means I still want suggestions on a automated system.