Make sure the water is within the temperature range of your gadget, then insert your hydrometer and spin it. It should settle with a specific gravity of 1.000. If it's too high, carefully file from the bottom of your hydrometer until it's correctly seated. Too low and you might need more or less water.
The specific gravity of water is important because it tells us about the amount of dissolved solids in the water. The more solid particles, like minerals or salts, that can be found in water, the higher its density will be. Pure water has a density of 1g/L on average but may vary depending on how far north you are (ice melts at 0°C/32°F). Drinking water tends to be slightly denser than lake water which is itself slightly denser than ocean water.
Mineral content in water affects its appearance and odor. For example, water with a high salt content will appear more salty and smell worse. Water contaminated with chemicals such as acids or bases will also smell bad. Water contaminated with bacteria or other organisms that make it undrinkable takes on a green color when exposed to sunlight. This is called "sunburned" water and is not suitable for consumption without treatment.
Drinking water that is not properly treated can lead to health problems.
Calculate the density of water. Place the hydrometer in the water, gently spin it to remove any air bubbles, and then wait for it to settle. If the hydrometer is precisely calibrated, it will register 1.00 for pure water. The Plato or Balling scale hydrometer will read 0.00. The SG (specific gravity) hydrometer will read approximately 1.000 for pure water.
The specific gravity of your wort should be about 1.050-1.075. If it's lower than that, you need more sugar; if it's higher than that, you need less sugar.
You can also use an accurate scale to measure out a fixed amount of dry malt extract. Then adjust the recipe accordingly so you get the same amount of sugars after fermentation as you did before.
Finally, you can use an online tool like this one from BeerTools to calculate the exact amount of sugars in your wort. It's based on your original gravity and the amount of malt extract you use in the recipe.
For example, if you calculate that your wort has 5% alcohol by volume (abv), then it contains 50 grams of sugar per liter of water.
When floating in clean water, your hydrometer should register 1.000 if it is properly calibrated. Because water density varies with temperature, hydrometers are designed to be used at a specified temperature (60 °F/16 °C or 68 °F/20 °C). When dipping a hydrometer into water, allow it to float for several minutes before taking its reading. This allows any air bubbles inside the glass to rise to the top.
The amount by which your hydrometer dips below 1.000 indicates how much sugar is in your honey. If it dips below 0.900, that means you have under-sugarized your honey; if it dips below 0.800, that means you have oversugared it. And don't worry about whether the number is higher or lower than 1.000. That's what makes honey such an amazing food: even though it's a sucrose solution, it still floats!
Hydrometers can be bought online and at some craft stores, or you can make your own out of thin glass tubes and a plastic hydrometer from a science kit. They work by measuring the weight of the liquid above a given volume of air. Since water density is temperature dependent, you need to adjust your reading for the temperature of the water you're using.
Hydrometer. This simple device measures the relative density of liquids by comparing their heights in a container. The lower the liquid, the greater its density compared to water.
How does a hydrometer work? When you pour a liquid into a hydrometer tube, the weight of the sample will vary depending on the type of liquid. Lighter fluids such as water or milk will fill the tube, while heavier ones like oil or wine will sit at the bottom. By measuring the height of the sample in the tube, you can estimate its average weight per volume unit (specific gravity). You can use this information to determine the percentage of alcohol in your sample. For example, if the sample reaches from the top of the tube to just below the surface, then it has an approximate alcohol content of 3%.
The advantage of using a hydrometer instead of a refractometer is that you can also measure substances other than alcohol that affect the refractive index of the liquid. For example, sugar affects the reading of a refractometer but not that of a hydrometer.
Fill the urinometer cylinder halfway with urine and insert the urinometer float. Check that the float is not in touch with the cylinder's sides or bottom. Using the bottom of the meniscus, read the specific gravity on the scale on the urinometer stem. Record the reading.
Specific gravity can also be measured using a laboratory test called an "urine dipstick." You will need a urine dipstick kit for this procedure. There are different types of dipsticks available, but they all work on similar principles. First, add a small amount of urine to the test strip wells. Then place the test strips into a solution of water and sodium hydroxide (lye) to determine their color. A blue-colored well means protein is present in the urine; if there is red dye in the well, it means blood is in the urine. A yellow-colored well means glucose is present in the urine; if there is orange dye in the well, it means ketones are also present.
You can use these results to make a diagnosis of diabetes mellitus. The presence of glucose in the urine indicates that diabetes has been recently diagnosed or that someone has hyperglycemia due to any cause other than insulin. If protein is also present, then the patient has nephropathy, which is generally more severe than simply having diabetic microangiopathy.