People can have a conversation without arguing, I'm not trying to slight you or argue with you. If you want something to be helpful, it at least needs to be factually accurate. Red Sea blue bucket typically has an alkalinity of 8-9 dKh (we'll call it 8.5). The measured difference you had the last seven years has no bearing because you attempted to use a different salt. Your undata didn't die because it cant tolerate something outside of 9.8-10.1 dKh. Mine has been fine all the way down to 6.4 dKh. Thousands of reefers have them in parameters all over the place.
Again, if 10 dKh is working for you, absolutely stick with it but if we're trying to be helpful to other reefers, suggesting that the change of salt or lower alkalinity was the cause is just false.