To use a hydrometer correctly, place it in the beer or wine to be tested. Either lift or spin the hydrometer to dislodge any gas bubbles that may have gathered on it then allow it to settle and float freely. Take a reading directly from the scale at the surface of the liquid.
The sole use of the hydrometer is to show the specific gravity (S.G.) or "thickness" of any liquid. For the wine or beer maker it shows the concentration of sugar in solution. However, it can also indicate the concentration of alcohol in a beer. By taking a reading at the start of fermentation and another at the end and dividing the difference by 7.36 it will show the alcohol produced. For example, a start reading of 1050 and an end reading of 1005 will give a difference of 45. Dividing this by 7.36 will give an alcohol content of 6.1% by volume. With the addition of 1 teaspoon of sugar to your beer bottles your alcohol content will increase by 0.3% for a total of 6.4%.
It is easiest to store the hydrometer in a chlorine solution in the container it came in. Not many of us have the time to sterilise it for 2 hours and use it for 2 seconds!! By storing it this way all you need to do is rinse it under the tap, place it in the brew, take the reading and put it back in the container.
Takes less than 30 seconds... Simple!!!!!