First things first.
YOU NEED ONE and YOU SHOULDN’T MAKE BEER WITHOUT IT!

Now that you have one what does it do, what do you do with it, how do you read it, why do I need it? We will take it step by step in an attempt to understand its use.

What does it do: The primary purpose for the hydrometer is to take gravity readings of a liquid. The liquid could be water, oil, wort, beer, or any other liquid.

What do you do with it: For testing purposes we are going to test water. Take the hydrometer and remove the lid/cap on the container. Add water to the container until the hydrometer floats. Most water will have an “corrected” specific gravity of 1.000. So what do you mean “corrected” specific gravity? In order to get the corrected specific gravity you must first take a temperature reading of the liquid, in this case water. So get a thermometer and take a temprature reading of your water out of the tap. Most hydrometers are calibrated to either 60 or 68 deg. F. Yours should be clearly marked on the paper inside the hydrometer.

Below is the temperature correction chart I use. Note: my Hydrometer is set for 60 deg. F.

Using the example from above, if your reading was 1.001 you would have a corrected gravity of 1.002.

How do you read it: The hydrometer is read by looking at the top level of the liquid as it meets the hydrometer. You may want to spin the hydrometer in the tube in order to remove any bubbles adhering to the outside of the hydrometer. Bubbles will give you a false reading.

Why do I need it: Simply put, you need know when your beer is finished fermenting. This is done by taking an Original Gravity (OG) and a Final Gravity (FG) reading when making beer. Whether you are transferring to a secondary fermenter for clearing, bottling, or Kegging. If you transfer to secondary to early, your beer may not finish fermenting. Your wort will be sweet to taste, this could lead to what is know as Bottle Bombs! Believe me this is not something you want! NOTE: If your wort is sweet to taste, contact your local Home Brew Shop BEFORE you bottle it!

Recap:

• Your hydrometer takes gravity readings of a liquid.
• You will need to know the temp of the liquid being measured.
• The reading is taken from the top level of the liquid.
• And most importantly, you need to know when your beer is finished fermenting.

Hope this helps clear up any confusion about Hydrometers and why you need them when brewing beer.

Cheers

Preston