Gypsum, the solution?

[Whorst]

http://www.antiochsudsuckers.com/tom/brewingwater.htm

Take a look at 6.0 and 6.1.

Why are we discussing acid additions to lower alkalinity, when apparently enough Gypsum lowers it?

"Remember that when we defined alkalinity, we said it was HCO3- + CO3-- (no SO4-- term), so although gypsum (CaSO4) adds calcium it does not contribute to alkalinity, but as we will discover later, it does reduce ‘Residual’ Alkalinity." This makes sense as Burton water was high in bicarbonate, but was offset by high calcium levels.

According to the equation: RA = Alkalinity (ppm as CaCO3) - 0.714 x Ca (ppm) - 0.585 x Mg (ppm)
So, if my residual alkalinity is 29, why add acid?

[Whorst]

My alkalinity is around 93, but when I plug in all the numbers, which include my gypsum addition, I get 290688.615. I've already added 1/4 teaspoon of lactic acid, which may have been unnecessary.

[Whorst]

93 ppm.

[Whorst]

I just spoke to a guy at my water district. It's expressed as CaCO3.

Residual Alkalinity (RA) = Alkalinity - Ca / 3.5 - Mg / 7, where all are in ppm as CaCO3

Using this formula in my application you get:

93-150/3.5 - 21/7
= 93 - 43 - 3
= 47

Without the calcium addition: 93-46/3.5 - 21/7
= 93 - 13.14 - 3
= 77

I'm thinking 1/4 teaspoon of lactic acid along with a healthy calcium and calcium chloride addition would be adequate for Bitter if this formula is accurate.

[Whorst]

Thanks for your help Chris. I think I'm on the right track now.