I have a small 2.5 gallon keg in my kegerator system that is used for carbonated water that my wife likes to drink. I understand that carbonating the water will lower the pH some and my wife is on the kick where drinking water with a higher pH level is better for you. Leaving all that alone, I was using Bru’N Water to see if I could calculate the amount of pH gain I will get from using baking soda in 2.5 gallons of my tap water (which has been tested and used with Bru’N Water for many many batches of beer). My starting pH is 8 on my tap water. I leave the grain bill page empty and set me mash volume to 2.5 gallons of water on the water adjustment page. With no chemicals entered, I get a estimated mash pH of 6. I am confused as to why the mash pH doesn’t come out as 8 with no adjustments made what so ever.
What water profile are you using?
Set the profile to “user custom”, that will eliminate all the salts associated with a profile.
It may be a “Divide by Zero” issue. Without any grain input on that grain bill tab the water to grist ratio returns an error. If you add some amount of grain it will change, then removing the grain the pH does not adjust. Perhaps enter in an amount of grain to get the pH to match, then add your salts to adjust to your desired pH?
The program won’t help you answer that question. Its not intended to assess and predict that condition.