1. What is Residual Alkalinity?

Residual Alkalinity (RA) is a key parameter in brewing water chemistry that represents the alkalinity remaining after accounting for the precipitation of calcium and magnesium. It helps brewers understand how their water will affect mash pH and ultimately beer flavor.

2. How Does the Calculator Work?

The calculator uses the Residual Alkalinity formula:

Where:

• \( Alkalinity \) — Total alkalinity in ppm as CaCO3
• \( Ca \) — Calcium concentration in ppm
• \( Mg \) — Magnesium concentration in ppm

Explanation: The formula accounts for how calcium and magnesium ions reduce the effective alkalinity in brewing water by forming insoluble compounds during mashing.

3. Importance of Residual Alkalinity in Brewing

Details: Residual Alkalinity is crucial for predicting mash pH, which affects enzyme activity, starch conversion, and ultimately beer flavor. Different beer styles require different RA levels to achieve optimal mash pH.

4. Using the Calculator

Tips: Enter your water profile values for alkalinity, calcium, and magnesium in ppm. All values must be non-negative numbers. The calculator will compute the residual alkalinity in ppm as CaCO3.

5. Frequently Asked Questions (FAQ)

Q1: What is a good RA range for brewing?
A: Ideal RA depends on beer style: -150 to -50 for pale beers, -50 to 0 for amber beers, and 0 to 150 for dark beers.

Q2: How does RA affect mash pH?
A: Higher RA leads to higher mash pH, which can result in lower efficiency and different flavor extraction.

Q3: Can I adjust RA in my brewing water?
A: Yes, by adding brewing salts (calcium sulfate, calcium chloride) or acids to reduce alkalinity, or adding alkaline compounds to increase it.

Q4: Why are the divisors 3.5 and 7 in the formula?
A: These values represent the equivalent weights of calcium and magnesium carbonate relative to calcium carbonate.

Q5: Is RA the only factor affecting mash pH?
A: No, malt composition also significantly affects mash pH, but RA helps predict the water's contribution.