[alekmager]

Hey just wondering if there's anyway to find out how much one teaspoon of gypsum affects pH in 1 gallon of water? Also how else can you adjust base pH of water to better suit a brew day?

[BrewBama]

I believe Gypsum is neutral in pH, and since it has no carbonate ion as part of its makeup, it will not neutralize acidity.  This blurb from Bru’n water does not mention it lowering pH either:

“Gypsum provides calcium and sulfate ions for brewing water.  Although gypsum has limited solubility in water, it is readily soluble in water at the concentrations typically used for brewing.  The solubility limit for gypsum in boiling water is about 1.6 grams per liter of water.  That dosing rate would approach 400 ppm calcium and 900 ppm sulfate which is far higher than recommended for brewing water.  Therefore, gypsum can be considered readily soluble at typical brewing water usage rates.  Gypsum is more soluble in cool to warm water (maximum gypsum solubility occurs at around 40C or 100F) and should be added to water prior to boiling for quicker dissolution.  Vigorous stirring is typically required to speed the gypsum dissolution.  If gypsum does not dissolve in a timely manner when added to water at less than 1.6 grams per liter, test the gypsum for the presence of chalk by adding an acid such as vinegar or lactic to the dry powder.  If the mixture 'fizzes', the gypsum is adulterated with chalk.  Gypsum is also known by its chemical name: calcium sulfate dihydrate and its chemical formula is: CaSO4·2H2O.  Gypsum does not readily pick up moisture from the air.  Gypsum is typically available from brewing supply stores.   A gypsum addition of 1 gram per gallon, increases the calcium content of the water by about 61 ppm and the sulfate content by about 147 ppm.  An addition of 1 gram per liter, increases the calcium content of the water by about 232 ppm and the sulfate content by about 558 ppm.”

https://sites.google.com/site/brunwater/water-knowledge



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[Robert]

The pH of the water itself is totally irrelevant.  This can't be stressed enough.  It is only the pH of the mash, as measured at room temperature, that we're interested in.  That is a product of the interactions of a specific grist and the ions in the water.  Every individual grist will have its own pH in deionized water, and will have its pH shifted differently by different ions.  For a great introduction to the subject of water chemistry and mash pH, go to the Bru'n Water website and read the Water Knowledge page.  Then the spreadsheet there can help you plan water treatment to get the right pH in your particular recipe.

[hopfenundmalz]

Ca will reduce pH in the mash when it reacts with the phytin from malt in the mash, and releases an H+ ion.

No Phytin, no pH reduction, so nothing happens in water.

See Robert’s reply as to why your question is indeterminate - not enough inputs defined.