Refractometer different on SG to hydrometer

[Brettman2]

I have been using a hydrometer for years and finally lashed out and got a refractometer recently. I know that after the wort starts to ferment, the refractometer will not read accurately. But from what I have understood, the two instruments should read the same on starting gravity.I have noticed a discrepancy of between 3 and 5 points between the refract and hydrometer. (The hydrometer reads higher than the refract.) I have checked both with distilled water and they both read 1000. Does anyone have a similar problem or know if this is to be expected? Thanks

 

[Barge]

I'm no expert by any means but here goes.

My refractometer only reads in Brix. I have to use software to convert this to an S.G. reading. To make it accurate I set the refrac to 0 Brix in distilled water. I then prepared a 1.030 solution with malt extract, confirmed with the hydro and then took a Brix reading. I put this reading into the software and it calculates a correction factor. Every time thereafter I can just use the Brix and software to tell me what the hydro would read. I use this during mash/boil etc; basically pre-ferment. During fermentation and after I use the hydro only.

 

[Brettman2]

I'm no expert by any means but here goes.

My refractometer only reads in Brix. I have to use software to convert this to an S.G. reading. To make it accurate I set the refrac to 0 Brix in distilled water. I then prepared a 1.030 solution with malt extract, confirmed with the hydro and then took a Brix reading. I put this reading into the software and it calculates a correction factor. Every time thereafter I can just use the Brix and software to tell me what the hydro would read. I use this during mash/boil etc; basically pre-ferment. During fermentation and after I use the hydro only.

This refract has both the Brix and SG scale. Perhaps it's worth doing a check like you did with the 1030 solution to see what it reads. Thanks Barge.

 

[Tropico]

Barge is right. When reading wort you have to apply a "Wort Correction Factor" to refractometer reading to get accurate reading, either Brix or SG. When using sugar (sucrose) in solution, it should be accurate without correction.

My understanding is that "Wort Correction Factor" also changes for different types of wort.

 

[danestead]

All the above replies are correct. You should be right to go once you have figured out your wort correction factor. Mine was 1.04 and I usually brew using all grain so a figure similar to that should work for you if you also don't use adjuncts etc.

Disregard the SG scale on your refractometer if it has one. Use brix. The SG is likely wrong.

 

[JDW81]

I have been using a hydrometer for years and finally lashed out and got a refractometer recently. I know that after the wort starts to ferment, the refractometer will not read accurately. But from what I have understood, the two instruments should read the same on starting gravity.I have noticed a discrepancy of between 3 and 5 points between the refract and hydrometer. (The hydrometer reads higher than the refract.) I have checked both with distilled water and they both read 1000. Does anyone have a similar problem or know if this is to be expected? Thanks

What temperature are you sampling your wort at? If it is cold, the hydrometer will read a few points higher than the refractometer. I.e if your OG is 1050, and your wort is at 10 degrees it will read 2 points higher than the refractometer, the same goes for warm wort (1050 on a refract will read 1048 at 30 degrees on the hydrometer).

JD