If you have been homebrewing for a while, you are already aware that unexpected things can happen. It's possible that your beer won't ferment because you used a faulty batch of yeast. Alternatively, your yeast may ferment so fast that you're afraid it didn't. Or with just one beer, Uncle Lachie can be far more drunk than he should be.
Your hydrometer can save the day—and your uncle's liver—in this situation. Despite being quick and simple, this phase in the brewing process is frequently disregarded. Develop the practice of utilising them in each batch to test your estimated alcohol by volume (ABV), maintain consistent results, and ascertain whether your fermentation is complete.
Hydrometers
In a light liquid, a floating body sinks more deeply than in a heavy one. The hydrometer (a Greek that means "water measurer" is a tool that uses this idea for figuring out a liquid's properties, including its density or weight per unit volume. Usually a sealed glass tube, the hydrometer is marked with a scale and weighted at one end to maintain its upright position. The density of the liquid determines how deep the flotation occurs when submerged in the fluid being measured. The tube's neck scale is calibrated to measure density or specific gravity.
In beer making, we use a reliable brewing hydrometer to get two main pieces of information on dissolved malt extract and other sugars in our wort or beer as it ferments.
- Specific gravity. Firstly, specific gravity helps track the fermentation progress of your beer. Before fermentation starts, the gravity is at its highest, called the original gravity (OG). As yeast converts malt sugars into CO₂ and alcohol, gravity readings steadily drop. During active fermentation, visible signs like bubbling indicate the process is ongoing, so frequent readings aren’t necessary. Once fermentation completes, the gravity stabilises at a final gravity (FG). Consistent readings over 24-48 hours confirm it’s time to bottle or keg your beer.
- Alcohol by volume. A hydrometer also estimates the alcohol content of your brew. It uses a potential alcohol (PA) scale, showing the alcohol level if all sugars were fully fermented. PA is highest before fermentation and lowest when yeast consumes all fermentable sugars. To calculate the alcohol content, note the PA before and after fermentation. Subtract the final PA from the initial PA. For example, if a brew starts with a PA of 6% and ends at 2%, subtracting 2 from 6 gives an alcohol content of approximately 4%. This simple formula helps determine your beer’s strength using hydrometer readings, making it an essential tool for homebrewers.
How to Choose a Hydrometer?
You’ll notice three types when choosing a reliable brewing hydrometer. Here’s what you need to know about each variety to pick the best option.
Triple Scale Hydrometer
At about $5 to $15, this is the most affordable and widely used hydrometer. It has multiple uses and measures potential alcohol, Brix/Balling scale, and specific gravity. One size fits most batches because this brewing hydrometer measures a larger specific gravity range (0.00–1.170). However, because the device can measure a wider range of numbers, that also means your readings may be slightly off.
Thermohydrometer
Temperature and specific gravity are measured by the thermohydrometer. You run the danger of getting erroneous results if you don't use the same thermometer each time you test because different devices have different calibrations. However, the integrated thermometer guarantees a constant temperature. With two instruments in one, the $10–$15 price range is excellent.
Precision Hydrometer
You can obtain a more precise measurement with the precision hydrometer since the numbers are separated on a smaller scale when measuring specific gravity. However, depending on what you're brewing, you might need to purchase two hydrometers. While the majority of other hydrometers range between 0.00 and 1.170, some measure between 1.000 and 1.070, while others measure between 1.060 and 1.130.
Refractometers
If you ask yourself: "What can I use instead of a hydrometer for home brew?", the answer is a refractometer. This tool offers a modern alternative for measuring sugar content. Unlike a hydrometer, it gauges the refraction of light through the liquid rather than its density.
Benefits of Using a Refractometer
There are several key benefits to using refractometers.
Minimal Sample Size
Refractometers require only a few drops of wort, leaving more in your fermenter for packaging—a clear advantage when conserving your brew is a priority. A typical sample size might be as little as two or three drops, meaning you can measure gravity without compromising your batch volume. This is especially helpful for brewers working with small batches.
Reduced Temperature Sensitivity
Since refractometer samples are small, they cool quickly, reducing temperature-related errors. Many models also feature automatic temperature compensation, further enhancing accuracy without additional manual adjustments.
Less Equipment Needed
With a refractometer, there’s no need for a thief, graduated cylinder, or thermometer. A simple, sanitised pipette or dropper is sufficient for obtaining samples. This streamlined setup is perfect for homebrewers looking to minimise clutter and simplify the brewing process.
Lower Contamination Risk
Because you can extract a sample through the airlock using a pipette, exposure to open air is minimal. This reduces the likelihood of contamination and allows for more frequent sampling to track fermentation progress. Thanks to their precision and convenience, refractometers enable faster, more frequent readings throughout the brewing process. For instance, you can easily monitor pre-boil gravity and mash efficiency without interrupting your workflow. The ability to take real-time readings during critical stages of brewing allows you to adjust mash times, temperatures, and other variables for better control over your final product.
The Final Verdict
In summary, both hydrometers and refractometers are valuable tools for homebrewers, each with distinct strengths. Hydrometers are cost-effective and reliable but require larger samples and careful temperature management.
Refractometers, while generally more expensive, offer speed, precision, and minimal waste. Choosing the right tool depends on your brewing style, budget, and priorities—but investing in accurate gravity measurements is a sure way to elevate your beer-making game.
