Since I have new plaster, a concern is scaling over the winter due to a likely continual rise in pH. It was suggested to me both here and by my plasterer to leave the CH around 200. With a TA level of currently 65, I noticed that if I keep the pH around 7.6, the SI goes into the corrosive zone, especially as the water temperature lowers. The lower the water temp, the worse the SI reading goes (like down to -0.65); however, if the pH is kept around 8 or even slightly higher, the SI maintains itself around -0.25. So should I aim to keep the pH slightly higher after closing? Or not worry about it since it will probably go up anyway? It seems that, contrary to what I would have thought, the higher pH (to a certain point anyway) actually protects the overall balance from going into the scaling zone. Perhaps some of what seems to contradict logic in all of this is my using a constant and unchanging TA number when I run the different scenarios in the SI calculator. I suppose that if the pH continue to go up during the winter, the TA will also(?) So should I shoot to keep the pH around 8 if possible? My greater concern, and perhaps a needless one with the new plaster, is to avoid etching more than scaling. As my plasterer has told me, you can take it off but you can't put it back on! Thanks for any advice.