« on: February 28, 2014, 01:53:03 PM »
The pH may actually be below 4 because the strip bottomed out. Take a sample of the beer (~10 ml) and measure the pH. Now add a drop of StarSan to the sample, stir and take pH. If the pH reading didn't change the strip is bottomed out and the pH could be below 4.
OR you could measure the pH with a pH strip for wine.
I've used calcium carbonate before. A little bit goes a long way. Unless you've get a scale that is good to a fractions of a gram it'll be hard to test adding calcium carbonate to a small sample of beer and then scale up for the whole batch.
You can add a little calcium carbonate (purchase at wine store with pH strips for wine) and add maybe a 1/10th of a tsp of calcium carbonate, shake your fermenter a bunch, and see how much the pH changes. You will probably get a lot of CO2 coming off both from the fermentation and from the neutralization of the calcium carbonate. It is very easy to overshoot the additions as the pH can suddenly change as you approach a "tipping point."
You could probably also get some good advice from your local wine supply as adjusting the pH of wine is fairly standard.