Build up starter of lacto with Jarrow Ideal Bowel Support Probiotics. I used 10 capsules in a starter (3 pints water, 1.5 cups DME). I let it sour on a heat pad for a couple of days, chilled and decanted liquid, repitched lacto into another starter. Let it sour a few more days, save slurry for brew day.

Acidulated malt of 0.75 lb assumes starting with 8 gallons of mash RO water with a pH of 5.5. These quantities of water assumptions and grist are targeting a mash pH of 5.3.

After sparge is complete, drop wort pH to 4.5 using food grade lactic or citric acid. First experience: I had 14 after transferring back to MLT (sight glass showed 13, but an additional gallon in HERMS coil, pump, hoses, etc.) and pH was 5.3. I added 13 grams of citric acid, and this dropped the pH to 4.7.

Bring to boil and boil for 3 minutes. Add enough water in HLT to cover HERMS coil, and bring to temp to 90. Chill wort to temp of 90 while pumping wort back to the MLT. Minimize aeration. When HLT is holding 90, pitch the lacto into the wort. Recirculate wort through the HERMS coil, and check pH regularly. Once wort reaches 3.5 pH, transfer to BK. Boil and hop per schedule. Chill to 80 degrees, pitch WLP 644 from decanted starter without aerating. Hold temp at 75 during fermentation.

NOTE: Lacto plantarum works VERY quickly at 90 degrees. In my first experience, I started souring at 115 and progress was very slow... from 4.7 to 4.4-4.5 in 24 hours. I dropped the temp to 90, and 12 hours later, it was down to 3.7. I then raised the temp to 120 to slow the souring process while I was at work. 9 hours later, the pH was down to 3.5-3.6. I boiled at this point.