JohnR13 Posted May 15, 2012 Share Posted May 15, 2012 Hi Guys, Have a question about hydrometer readings. I've been brewing on and off for years, kits only, and have always used previous experience as to when to bottle. I have lately started to get a bit more experimental and have been using the hydrometer to determine when to bottle which works fine. I decided to start checking OG and FG to determine my ABV but first brew I've checked is suss. Did the Coopers mild ale to the recipe and got OG of 1024 and FG of 1006. Used the ABV calc from this forum (the formula looks correct) and got 2.9% but the recipe suggested 3.5%. Am I reading the hydrometer slightly out or is there some other factor that might be skewing my reading. Would like to get it accurate as many recipes I follow dont quote the ABV, and I dont always use set amounts of fermentables. Any help appreciated. Cheers JR Link to comment Share on other sites More sharing options...
GregT5 Posted May 15, 2012 Share Posted May 15, 2012 John, a couple of things you could try. Test your hydrometer in water at 20 degrees. I have 2 hydros, one is glass & the other is one of the plastic ones from the DIY kit. They both give a different reading so I adjust my figures accordingly. The other thing which could affect your readings is the gas in your samples. I draw off a part sample & discard it. I then take another sample & shake/stir it until it is flat then take a reading. Bubbles on the hydro will give a false reading. I have found this has resulted in more accurate readings. One other thing, with the formula you used to calculate your ABV did you add 0.5% for bottle conditioning? Hope this helps. Link to comment Share on other sites More sharing options...
JohnR13 Posted May 15, 2012 Author Share Posted May 15, 2012 Thanks Greg, I haven't calibrated either one. I have a glass one and the plastic one from the coopers kit I just bought. The plastic is easier to read. I did notice a lot of bubbles in the sample and although I spun the hydrometer, maybe I should try to degas first. The calc I used has the 0.5% for bottling and uses 7.46 as the calc. Cheers JR Link to comment Share on other sites More sharing options...
The Brew Master Posted May 15, 2012 Share Posted May 15, 2012 Hi John, Did you dissolve your fermentables completely? If not this will give you a false OG reading. I have brewed 4 "Mild Ales" recently & they are all about 3.5% Cheers, Peter Link to comment Share on other sites More sharing options...
Hairy Posted May 16, 2012 Share Posted May 16, 2012 Checking the callibration of your hydrometer will help you determine the correct OG & FG but won't change the alcohol content. For example, if it was out 5 points, then both your OG & FG will be out 5 points. The difference between the two would be the same. However, it is still a good idea to check it so that you can tell that you have reached your expected FG. Link to comment Share on other sites More sharing options...
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