Which is right and which is wrong?

[Rolly]

My hydrometer is showing me 1.065 in 60 degree wort. My brand new refractometer with auto temp correction, which I just calibrated with RO water, is showing me 1.060 also with 60 degree wort.

Would the refractometer be guaranteed correct because I'm able to calibrate it? This would mean that every batch I've done so far has been 5 points below where I thought it was

Can hydrometers be wrong? I'd hate to have to go buy another hydrometer just for a third party opinion.

By the way, the refractometer was $60 from AHS, so it's not some toy I won at the county fair or anything.

 

[usfmikeb]

I always calibrate my refractometer with distilled water, not sure how different RO would be.

 

[arturo7]

Trust the hydro. (assuming it is calibrated)

 

[Rolly]

Trust the hydro. (assuming it is calibrated)

Well there's no way for me to calibrate the hydro manually. If the refractometer isn't accurate then whats's the point in even using it? Maybe I'll just have to send it back.

 

[Vector]

If you really want to dig into this you should read this article: Trust, But Verify: Calibration of Hydrometers

It shows a procedures to check your Hydro at 2 different levels. The author had a one good Hydro and a bad Hydro.

 

[mcaple1]

Well there's no way for me to calibrate the hydro manually. If the refractometer isn't accurate then whats's the point in even using it? Maybe I'll just have to send it back.

what do you mean you can't calibrate a hydrometer. drop it into some distilled water and see where it lands...if it is off, then your calibration will be to add or subtract the factor to which it is off. derrr.

 

[JuanMoore]

Well there's no way for me to calibrate the hydro manually.

Calibrate might not be the technically correct term, but you certainly can (and absolutely should) check that it reads 1.0000 in 60F distilled water (assuming the hydro is calibrated for 60F). It's a good idea to do this periodically, since the paper inside can slip a little. If it does slip and reads 1.002 for example, then you know to subtract 0.002 from all of your readings. You can also go into more depth by following the link above.

If the refractometer isn't accurate then whats's the point in even using it? Maybe I'll just have to send it back.

The main advantage to a refractometer is that it only takes a few drops to get a reading, which is much faster to cool than a couple ounces for a hydrometer reading. Since I have a very consistent/predictable system and process, I rarely mess with any SG readings other than the OG and FG, so I have no real use for one. If I were a fly sparger or liked to take a lot of SG readings, a refractometer would be really handy.

And in case you weren't aware, the refractometer won't be even close to accurate once there's alcohol present (even using the alcohol correction calculators), so it's really only useful pre-fermentation.

 

[Catt22]

Well there's no way for me to calibrate the hydro manually. If the refractometer isn't accurate then whats's the point in even using it? Maybe I'll just have to send it back.

You can easily check the hydrometer with water. It should read 1.000. When checking gravity with a refractometer, be sure to stir the wort well prior to mitigate possible stratification issues. It also pays to take more than one reading with the refractometer and if they don't agree, take additional readings until they do.

 

[cwi]

My hydrometer is showing me 1.065 in 60 degree wort. My brand new refractometer with auto temp correction, which I just calibrated with RO water, is showing me 1.060 also with 60 degree wort.

Unless a new model has been made in the last couple of months, the SG scale on the refractometers sold in LHBS have an inaccurate SG scale. A simplified Brix-SG conversion equation (if multiplying by a constant counts as an equation) was used resulting in an SG error that increases with Brix. Morebeer has a calculator to convert from Brix to SG more accurately.

By the way, the refractometer was $60 from AHS, so it's not some toy I won at the county fair or anything.

I would say that refractometers in the ~$50 range do fall into the "toy" category. These same models can be found online at non-homebrew places for ~$20. Not to say they aren't useful, but they aren't lab grade either- just like the hydros sold in LHBS.

Having said that, even lab grade gear needs to be calibrated. If it matters to you, the accuracy of these devices can be improved if you calibrate them closer to the expected usage range, rather than SG=1/Brix=0. The refract's Brix scale will still be the more accurate measurement as readings stray from the cal point, but the SG scale's error may be within reason for most HB purposes.

 

[ayoungrad]

I would say that refractometers in the ~$50 range do fall into the "toy" category. These same models can be found online at non-homebrew places for ~$20. Not to say they aren't useful, but they aren't lab grade either- just like the hydros sold in LHBS.

Where do you buy your equipment and what do you pay for it?

 

[BrewThruYou]

I would trust the hydro. I bought a similar refractometer and I barely use it.

 

[HairyDogBrewing]

The Brix scale was developed for solutions of sucrose.
Each degree of Brix is one percent sucrose, by mass.
So you can check your refractometer at 15 Brix by dissolving 15 grams of table sugar in 100 grams of distilled water.
This should have a specific gravity of 1.061 at 20 degrees Celsius.

Note that the solids in wort are mostly maltose, not sucrose.
Maltose solutions have a slightly different refractive index.
By consensus the correction factor is 1.04, I don't know if there is a more accurate value.
So at 15 Brix expect to see 1.063 on your hydrometer instead of 1.061.

 

[cwi]

I would say that refractometers in the ~$50 range do fall into the "toy" category. These same models can be found online at non-homebrew places for ~$20. Not to say they aren't useful, but they aren't lab grade either- just like the hydros sold in LHBS.

Where do you buy your equipment and what do you pay for it?

Why does it matter?
I was merely stating that these gadgets, like most things used in homebrewing, are not precision instruments, nor do they need to be.

I think my response about the incorrect scale (reads progressively lower than actual SG) on current cheap refracts is at least one source of the discrepancy between the two readings. There could be other influences since it was not stated whether the hydrometer was being read correctly (miniscus), although it was stated that it was not even calibrated with H2O. There are lots of other places for human error to creep in as well.

It just seems like the OP is focusing too much on numbers.
If sub .005 precision SG is desired, higher grade instruments may be needed throughout the process to make use of it. Maybe a .0000001 gram resolution scale for weighing hops.

The real benefit of a refractometer, as was stated previously, is quick and easy OG readings.

 

[cwi]

The Brix scale was developed for solutions of sucrose.
Each degree of Brix is one percent sucrose, by mass.
So you can check your refractometer at 15 Brix by dissolving 15 grams of table sugar in 100 grams of distilled water.
This should have a specific gravity of 1.061 at 20 degrees Celsius.

Note that the solids in wort are mostly maltose, not sucrose.
Maltose solutions have a slightly different refractive index.
By consensus the correction factor is 1.04, I don't know if there is a more accurate value.
So at 15 Brix expect to see 1.063 on your hydrometer instead of 1.061.

Morebeer has a Brix-SG calculator, but I don't have the link. It apparently has lots of correction factors like accounting for suspended solids, and difference between maltose, etc. I glanced at the equation, and it was not a simple multiplier constant.

The simplified formula SG = (.004*Brix) + 1 gives increasingly larger negative SG errors as Brix increases (converted SG is lower than actual SG by an increasing amount). According to Morebeer, the error becomes significant in homebrewing above 1.04.

 

[ayoungrad]

Why does it matter?
I was merely stating that these gadgets, like most things used in homebrewing, are not precision instruments, nor do they need to be.

I think my response about the incorrect scale (reads progressively lower than actual SG) on current cheap refracts is at least one source of the discrepancy between the two readings. There could be other influences since it was not stated whether the hydrometer was being read correctly (miniscus), although it was stated that it was not even calibrated with H2O. There are lots of other places for human error to creep in as well.

It just seems like the OP is focusing too much on numbers.
If sub .005 precision SG is desired, higher grade instruments may be needed throughout the process to make use of it. Maybe a .0000001 gram resolution scale for weighing hops.

The real benefit of a refractometer, as was stated previously, is quick and easy OG readings.

I just took issue with the word "toy". The word implies that those refractometers are of no use. But I do understand you do think they can be useful.

I have been using both for the last few batches (I think my refractometer was $60 also). I have one hydrometer that is slightly more precise than typical (it only reads up to 1.060 and is fairly delicate as a result of the size of it's stem). I calibrate the refractometer and hydrometer and calculate temperature effects for the hydrometer. Doing this, I find them equivalent in their readings. With these results I'm going to abandon using a hydrometer for pre-boil and OG measurements.

FWIW, there are new (and apparently slightly more accurate) linear and cubic correction equations, that I found a link to from this site, to adjust FG readings with the refractometer to account for the alcohol. I'm still using the hydrometer for FG but I've been checking both and the equations are actually not as bad as you might think - even at over 9% EtOH. That is to say that the results are at least fairly accurate compared with my hydrometers. But they also correlate fairly well with expected FGs based on OG and expected attenuation.

 

[cwi]

I just took issue with the word "toy". The word implies that those refractometers are of no use. But I do understand you do think they can be useful.

I have been using both for the last few batches (I think my refractometer was $60 also). I have one hydrometer that is slightly more precise than typical (it only reads up to 1.060 and is fairly delicate as a result of the size of it's stem). I calibrate the refractometer and hydrometer and calculate temperature effects for the hydrometer. Doing this, I find them equivalent in their readings. With these results I'm going to abandon using a hydrometer for pre-boil and OG measurements.

FWIW, there are new (and apparently slightly more accurate) linear and cubic correction equations, that I found a link to from this site, to adjust FG readings with the refractometer to account for the alcohol. I'm still using the hydrometer for FG but I've been checking both and the equations are actually not as bad as you might think - even at over 9% EtOH. That is to say that the results are at least fairly accurate compared with my hydrometers. But they also correlate fairly well with expected FGs based on OG and expected attenuation.

I believe I stated in my original post that even the cheap refractometers were useful. The "toy" comment was related to the comment by the OP that his refractometer was not a toy as it cost $60, and he was going to return it since it was disagreeing with his uncalibrated hydrometer by .005.

RE: FG readings- I never commented on them here. That was someone else. My comments regarding accuracy were related to the refractometer's SG scale being inaccurate for OG (or any SG, really). This is a known issue with all current refracts with an SG scale sold in LHBS. Whether it is a significant error, or not, is a personal choice. For best results, use the Brix reading, then convert it using a more complete conversion equation.

I am aware of the various FG conversion strategies. In my opinion, it seems more important to know whether the FG/Brix is still changing, than a high precision FG. A raw Brix reading will do that. Once the FG/Brix is stable, the Brix/OG to FG conversion equations should give a close a enough FG to know if it is stuck, or within style. For repeatability, the final raw Brix is probably good enough, or a hydrometer reading if you want more accuracy.

 

[ayoungrad]

Absolutely.

I didn't make a comment on the BRIX/SG scales on the refractometers because I agree with what you wrote. I largely ignore the SG scale on my refractometer and use the BRIX. I made my own brewing spreadsheet and I enter both values but I always assume that the BRIX is more accurate and I use that for subsequent calculations.

 

[Rolly]

Just to revive my old original post...I found the brix conversion spreadsheet at morebeer.com and using it makes my refract agree to my hydro to the .001