^ Basically, Yup.
To augment the argument against doing buffer additions - Once you do manage to get pH where you think it ought to be, what happens when you do a PWC? Unless you match the TDS, GH, KH & pH of the incoming water, you're going to throw the whole system out of balance, which stresses the fish a lot more than the initial pH swings you were initially worried about ever would have.
From week to week, most well & sity water systems deliver a fairly consistent product. This is a good thing. When you do a PWC and add water that's pretty similar to what you're taking out, all the fish will notice is that things are cleaner. There may be a slight shift in pH as a result of the nitrates, dissolved components of humus and fish waste that you aren't replacing, but you should still be fairly close on GH & KH (with no effort).