https://www.reef2reef.com/threads/co2-scrubber-without-skimmer.918381/This thread uses an airstone and co2 scrubbers to lower co2 and increase pH.
I JUST read through that yesterday!
He updated it at the end to say it had very little effect on larger tanks (I think his original tank was a 90?).
I started dosing kalk and my pH is much better now. I also started a refugium. The combination should work pretty well for me. :)