gravity reading question............

[madkap_78]

I just brewed my first two all grain brews about a week ago. They both have been in the fermenter about 7 days. I took a reading today of both of them with my hydrometer and my refractometer at 67 degrees f. Whats weird is the for the stout the refractometer says about 10.5 brix which comes out to 1.042 gravity, but when I use the hydrometer on it the reading says 1.020 which is kinda close to what it should be (1.018). For the IPA the brix is 9.2 which comes out to about 1.036 but the hydrometer reading says 1.016 which is exactly where I want to be. I tested the refractometer with some water and it reads zero, I also tested the hydrometer at room temperature water and it reads at 0% also. What gives, is it something Im missing or doing wrong? Have any of you come across something like this before? If there is any advice or feedback you can give me it would help greatly. I just started getting into brewing seriously and I want to get this down.

 

[3PegBrew]

Did you make sure all 3 samples were at the same temp for testing? If you calibrate your tools, you have to make sure everything is the same. Never came across this problem before when brewing.

 

[madkap_78]

I use the same sample for both the refractometer and the hydrometer. The wort was at 67f degrees. I wonder since these are my first all grain if it would have something to do with the mash temps or something. I got 1.069 post boil OG for both brews. When I test both the hydrometer and the refractometer in water they both read accurately. The hydrometer is giving me the numbers I am looking for. Plus isn't it impossible for a hydrometer to be incorrect? Don't they measure density, how would they be wrong?

 

[mvcorliss]

You cannot use the refractometer to measure SG once alcohol is produced unless you plug the numbers into a conversion calculator. Go with the hydrometer reading until you do some reading on the use of the refractometer after fermentation.

 

[BigFloyd]

Your hydrometer is correct, but you still need to leave it alone for another week before bottling.

Once alcohol is produced by fermentation, it throws the refractometer off and gives you an artificially high reading. There are programs out there to correct that, but I don't use my refractometer after pitching so I've not used any of them.

 

[madkap_78]

Thanks BigFloyd you put my mind at ease, I was freaking out for a min. One of these brews is a Christmas present for a friend of mine, so I want it to turn out good. I plan on leaving both of them in the primary for a total of 14 days anyway. I just took the gravity reading to see how they were coming along. So now I know for fementation to only use the hydrometer from now on.