I just started working to adjust my water, with an eye on getting appropriate salt balance and mash pH. We have quite high phosphates and total alkalinity, so I had been adding CaCl2 to control hop bitterness. Also, I've had some trouble getting proper mash conversion, which has ended up affecting my fermentability. My FG values have just been too high lately.
Using BrewersFriend.com's water chemistry calculator and my water chemistry (downloaded from my water company), this time I used phosphoric acid to adjust the strike water, aiming for a 5.3 pH for mashing. The BrewersFriend calculator takes into account the grain used, as darker grains tend to reduce pH on their own. So, I added CaCl2 as usual, and then the calculated amount of phosphoric acid. I measured my mash pH with a Hanna pH pen (after cooling), and it was at 5.27, quite close to the calculated value.
This beer started at 1.063 and ended at 1.013, pretty much exactly as anticipated. I'm not sure if the adjustment helped, but the mash led to great conversion and attenuation. Also, the malt/hop balance is perfect for this American Amber Ale. I will continue to do such adjustment, as it appears to help.