Hey, Baileys. Welcome to the forum! I just read your other thread. I found myself in a very similar situation... I bought a house with a pool with no idea what CYA really does or how to measure it accurately. My fill water is also very high in TA. It's a good idea to go ahead and test your fill water for hardness as well. As you refill evaporated water your pool will naturally rise in CH, assuming there's at least some hardness in your fill source. CH and CYA are two levels that never really decrease in pool water without dilution, and it already sounds like you've done that enough times already this season anyway. You may be seeing a slight reduction in your CH levels because your pool spent an undetermined time below 7.0 and your pool plaster is reabsorbing some calcium from the water. Keep an eye on it, but as long as you can keep the CSI in a good zone by manipulating your pH, you might want to hold off adding CH until you've got your TA situation in a more manageable place. For what it's worth, *pure* Calcium Chloride (ice melt) salt is the way to go, sometimes hard to find in the summertime, but with you being so far north you'll probably start seeing it. CaCl doesn't appear to significantly affect TA, as there's no carbonate in the mix.
What's most important now that you've done the refill is to get your CYA levels to 30, and get the pool swimmable with the correct amount of chlorine. Swimmers making lots of little bubbles will help that TA come down by ofgassing CO2, which will bring the pH up much faster than your PVC aerator tube which also helps cool the water and aerate. Other tricks include pointing returns up so they break the water's surface, running any overflow spa feature, spa bubbler, etc. Some folks hook up an air compressor to force air down into the pool to create more bubbles.
Take it nice and easy with the TA lowering, especially since your pool spent extended periods at a very low pH. Mine took almost 3 months to get where it doesn't feel like I'm dribbling a helium balloon with pH continually rising.
