Utilizing Phophoric Acid for Water pH Adjustment

Yesterday was another brew day. I'm trying to dial in my water adjustments for pale beers, specifically IPAs, so that is what I brewed once again. I focused on adjusting all my water and watching my pH for sparge and mash.

I started out by collecting 9 gallons of water early in the morning, adding 1/2 of a campden tablet and checking the starting pH. My meter was spot on at 7.7 with my last water analysis from less then a month ago. 

I used the Bru'n Water spreadsheet to calculate the amount of phosphoric acid I would need to bring my water down to a pH of 5.5. The spreadsheet indicated to add around 130 ml which I thought was a bit high. Thankfully for once I had the common sense (and soberness) not to just blindly trust the figure on the page.

I initially added 30 ml of a 10% solution of phosphoric acid to the 9 gallons of water I collected. I waited 15 minutes then checked my pH again and I was down to 6.5.  I repeated this step again except that I only added 15 ml then next time around. The result was a pH of 5.9. I added another 15 ml and the result was a pH of 5.3 which I should have known considering the changes the pH had taken in the last two rounds. To fix the over adjustment I added tap water at 4 cup increments and re-measured between each addition until I reached my 5.5 pH target after 12 cups.

So at that point I had 9.75 gallons of water adjusted with phosphoric acid to a pH of 5.5. I Collected 4.6 gallons into my mash tun for a 0.4 thickness mash with 11.5lbs of grain. After doughing in I waited 15 minutes then checked my pH which nailed my target mash pH at 5.2. The last time I brewed this IPA, I brewed it without the acid adjustment and simply added 10 grams of gypsum to gain a Burton on Trent like water profile. That time my pH was 5.8 so this is the first pale beer I have brewed where the mash pH landed in the commonly targeted 5.2-5.5 range. 

I checked my pH twice more throughout the mash and it held steady at 5.2. There are arguments both ways that you should/should not acidify your water to bring the mash pH into a target range, I simply decided to try it for myself and record the results here.

This beer is now fermenting in two buckets, in one I pitched a typical American ale use Safale US-05 and in the other I pitched an English ale yeast Safale US-04. This was just for fun so I could compare how the exact same wort would taste pitching two yeasts that I use frequently. Although I usually save the US-04 for my stouts so this should be interesting.

I will post again with the comparison of acid adjusted and non-adjusted water and another for the comparison in yeast strains. I’ll probably also eek another post out of this batch because I only added 7 grams of gypsum this time because the 10 grams in the last batch came out a tad salty and also 7 grams puts me in the 1:3 ratio of chloride to sulfate.