Originally Posted by hophop
The water ph is not the concern. Your mash ph is what we care about. You can easily adjust mash ph with a bit of lactic acid if needed.
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That is a true statement however you can help yourself by knowing what your ph is of your hot liquor. If your water source is above 5.8-6 then it would be good to go ahead and add some acid, (lactic-phosphoric), to your hot liquor to get it to what you need. If you are using light colored malts then 5.7-5.8 is a good starting point. Dark malts will lower your ph more as you mash so start at 6.0. As mentioned, check the ph during the mash to see how it's doing. If you need more acid then add it. Take notes on this so the next time you do this recipe you will know how much to add up front.
It's all about learning your system. Taking notes helps a lot, and not drinking till after the boil starts helps your notes make sense!!