Actually, I skimmed through the thread and someone asked him about if it would change the ph. to quote him.

" Sorry T-Rex... the answer to your questions is, mildly. My water comes out of the tap at 7.8-8.2. I change about 20% every month or so. The tank sits at 6.8-7.2, which I find ideal, even for shrimp.

When the aquarium has some carbonate buffering in it, the bicarbonate ions will combine with the excess hydrogen ions to form carbonic acid (H2CO3) which then slowly breaks down into CO2 and water. Since the excess hydrogen ions are used in the reaction, the pH does not change very much. Over time, as the carbonate ions are used up, the buffering capacity will drop and larger pH changes will be noted. From this it is clear why aquariums with low KH seem unstable - as acid is produced by biological action, the KH is used up; when it is gone, the pH is free to drop rapidly as H+ ions are generated. "