Crazy FG Help

[bulldogxray]

Ok so I measured my FG with a newly purchased recfractometer and it came out to 1.023. Not good on my 7th day in the primary, the refractometer seems right on when I put distilled water in it 1.000 it has atomatic temp control so that should not be an issue.

I decided to test with my trusty hydrometer, first I put it in distilled water and spot on at 1.000 and then I put it to some beer and 1.014. This is clsoer to what I want but how the hell can the refractometer be different especially if it is calibrated?

 

[Goathouse]

Sounds like a formula conversion issue.

Give this a look at see if it helps you.



http://morebeer.com/learn_vids/vids_refract

 

[mobly99]

Are you using corrected numbers? From what I recall, once alcohol is produced you have to use a calculator like this http://www.onebeer.net/refractometer.shtml

 

[bulldogxray]

Are you using corrected numbers? From what I recall, once alcohol is produced you have to use a calculator like this http://www.onebeer.net/refractometer.shtml

My refractometer has brix on one side and SG on the other so I am just reading the numbers.

 

[mobly99]

If you use the calculator and put in your starting brix and ending brix numbers you should get a FG number that comes pretty close to what your hydrometer reads.

 

[bulldogxray]

ok so I plugged the bix into the formula and it says exactly what my sg on the refractometer said 1.025, but my hydrometer says 1.015 which is what it should be. I put distilled water in the refractometer and it was right on and I put the hydrometer in distilled water and it was right on 1.000. so how does my fg different from the 2?

 

[JuanMoore]

#1) You need to use the formula to compensate for the alcohol present, not the formula for converting brix to SG. Alcohol messes up refractometer readings, so you need to have the OG in order to make the proper corrections.

#2) Even using the correct formula, refractometers are always going to be significantly less accurate than hydrometers as soon as alcohol is present. They're great for everything up to fermentation, but will only give a rough idea of SG after fermentation has started.

 

[bulldogxray]

#1) You need to use the formula to compensate for the alcohol present, not the formula for converting brix to SG. Alcohol messes up refractometer readings, so you need to have the OG in order to make the proper corrections.

#2) Even using the correct formula, refractometers are always going to be significantly less accurate than hydrometers as soon as alcohol is present. They're great for everything up to fermentation, but will only give a rough idea of SG after fermentation has started.

Thank you for clearing that up I did not know that.