I’ve used Bru’n Water for several years now. It’s always worked pretty well for me, and my measured pH has always been pretty close to what the program estimates. However, my last few batches have ended up pretty far from the estimate, and I was wondering if any of you could help me figure out what’s going on. I’ll give as many details as I can to help to figure this out.
- I’m measuring pH using a Thermoworks 8689. I don’t calibrate every single time, but I calibrated between the first and second batches I’m mentioning, and it didn’t have to change much with the recal. (So it seems to hold calibration pretty well.)
- I always measure pH at room temperature, or a little below. I pull a sample, and chill it down inside a cocktail shaker sitting in an ice bath. If I wait too long, it can get down to ~50F, but usually I measure around 60F or 70F.
- I take pH measurements every 10 minutes during the mash
- I’m using SF Bay Area tap water, filtered through a carbon filter, treated with Sodium Metabisulfite (might be Potassium? I’d have to check at home) for Chloramine. When I take water samples for testing, I always run it through the carbon filter for a direct comparison. I always run the filter at a trickle to collect water. It's typically very soft water.
- I've tested my water both using home lab kits and ward labs.
- I’m using Brew in A Bag methods, no-sparge. So I’m treating my full volume of strike water.
- I measure acid additions using a 10ml graduated cylinder
- I measure mineral additions using a high-accuracy gram scale, which I check with a 100g weight for accuracy.
- I typically add mineral additions and acid to the strike water before adding grains.
- I store my acid in the fridge.
- Batch 1:
- Style: Pre-Prohibition Lager
- Grist: 70% 6-row, 25% Red Malted Corn, 5% Flaked Rice
- Water tested using BruLab kit
- Water treated with no mineral additions, 6.39ml of 88% Lactic Acid
- Predicted pH: 5.24
- Measured pH: 5.85
- Batch 2:
- Style: Porter
- Grist: 70% Crisp Marris Otter, 10% Crystal 75, 5.6% White Wheat, 5.6% Chocolate Malt, 1.8% Carafe Special III, 1.8% Crystal 120, 5.6% Flaked Rice
- Water tested using BruLab kit
- Water treated with 0.58g salt, 2.1g Gypsum, .34g Calcium Chloride. No acid additions
- Predicted pH: 5.43
- Measured pH: 5.95
- Batch 3:
- Style: Cold IPA
- Grist: 75% Pilsner Malt, 25% White Malted Corn
- Water tested using Ward Labs
- Water treated with 3.5g Gypsum, 1.94g Calcium Chloride, 3.77ml of 88% Lactic Acid
- Predicted pH: 5.35
- Measured pH: 6.08 (!)