Reducing Bicarbonate with Slaked Lime
My water is 266 ppm of hardness as bicarbonate. Need to drop it. How much slaked lime could one use to treat the water pre-mash (night before)? And will this precipitate out calcium and magnesium that I will have to replenish?
Thank you! Cheers
Slaked lime will precipitate calcium in the form of calcium carbonate, and it can precipitate magnesium if alkalinity remains after the calcium supply is exhausted. Unless your magnesium is excessive, I'd just add enough lime to precipitate the calcium carbonate. What that amount is will depend on the total alkalinity, calcium concentration (after adding calcium chloride and/or calcium sulfate) and pH of your water supply. If you hope to have this be your only water treatment, it will also depend on your grainbill and water-to-grain ratio. However, I recommend removing as much alkalinity as possible from your total water volume (mash + sparge water) with slaked lime and adjusting the mash pH with lactic acid or calcium carbonate as needed. That way, the rise in last runnings pH will be minimal. I also recommend doing the treatment in a cold or ambient liquor tank to reduce baked-on chalk. If you need to do it under heat, using lactic acid for everything will give you better control and less mess.
Instead of us going back and forth about your water supply and all that, you should just enter your variables into my water chemistry spreadsheet. It's located at http://sites.google.com/site/republicbrewpub/ and the file name is Water_Barrels.xlsx.