Mg calculation question

[Duke145]

I have spent most of the day reading up on this and I have run out of time. In most of the worksheets to calculate water addition there is a spot for Mg. Now below is a section form my water report and it doesn't have that number but from reading up on this it can be calculated by subtracting the Ca hardness from the total hardness then converting that number.

Here is what I computed

Total hardness - Calcium hardness = Mg hardness

61-53 = 8

Then

Mg ppm = ( Mg hardness / 50) * 12.1

Mg ppm = 1.936

Is this close?

https://www.homebrewtalk.com/attachment.php?attachmentid=328776&stc=1&d=1452367428

 

[ajdelange]

Looks right to me.

 

[Duke145]

Thanks for the reply, many times when I think I have something figured out I'm dead wrong.