Refractometer and hydrometer not agreeing

[kohalajohn]

So, my hydrometer says 1052 and my refractometer says 1048.

I have been careful with my hydrometer readings. Spin the pipe, watch closely, ensure the surface tension is not messing up the view.

And I have carefully calibrated my refractometer. Cleaning it, adding room temp water, looking at it close to zero, taking the little screwdriver to adjust it so the water line shows exactly at zero.

Nope. I am still four points apart. Too much to ignore.

What do folk do in such circumstances?

 

[Deric]

Is this pre or post fermentation?

Are you correcting your hydrometer reading for temperature? Are you using a "wort correction factor" for your refractometer?

 

[kohalajohn]

Pre fermentation. OG.

Where would I find out more about "wort correction factor"

 

[worlddivides]

Pre fermentation. OG.

Where would I find out more about "wort correction factor"

https://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/

Although hydrometers can be wrong, hydrometers are more accurate than refractometers because hydrometers measure relative density, whereas refractometers measure light refraction.

If you tested your hydrometer with distilled water at 68F/20C and it read 1.000, then tested the wort at 68F/20C and it read 1.052, then the hydrometer is correct and the refractometer is incorrect.

 

[bike2brew]

Either one is close enough as your fermentation process is relative to the baseline measurement so pick one as your standard. The refractometer will need correction for alcohol but that's easy enough with the online calculator. Reading the little lines on the hydrometer is tough for my old eyes so I would probably use the refractometer however I have a Tilt and go with the digital readout

 

[dmtaylor]

Refractometers can only read in Brix accurately. If the refractometer has a specific gravity scale, it is only an estimate, and the estimate might be wrong. Measure only in Brix, then use the refractometer adjustment calculator at Brewer's Friend to determine the true specific gravity, experimenting with your own Wort Correction Factor until it reads right. My factor is 0.99, others report as high as 1.06. It's usually anywhere in about that range, close to 1.00 but not exactly 1.00. It is different for every instrument and every person using the instrument, but once you figure it out for YOU then it should remain constant from batch to batch within about 0.01-0.02. Different wort, different malt, etc. can cause this slight variability but it's pretty constant once you get it. Takes a few batches of trial & error to really nail it.

Be certain to use Part II of the calculator whenever alcohol is present. The alcohol skews the readings in a BIG way but in a very predictable way, accurate within 0.002 specific gravity points for most beers unless you're up in the 9%+ ABV area.

 

[Miraculix]

I'd check my hydrometer with a calibrated sugar solution. You can find tables online which determine how much table sugar in 100ml water is needed for a given gravity. Use a precision scale and you should be able to see who's right.

I've found interesting things in some of my hydrometers. Some were very off and the worse, it was not constant. They were almost spot on in plain water but a few points of at 1.05 og.

 

[kohalajohn]

That is helpful, thanks.

I'm with @bike2brew in that at my age, it is difficult to exactly see where the hydrometer is floating.

And while all the subsequent info abut calibrating refractometers is helpful, it's a bit of a thing.

You know, I always thought the kegland Pill tilt system was a silly thing. Just an unnecessary gadget, like wifi in a dishwasher.

But now I"m thinking, well, a refractometer is sixty bucks and so is a Pill.

Should I take the red pill or the blue pill, as Morpheus says?

It the least, I'm going to read about this.

 

[kohalajohn]

If entering the world of the Pill would make my lfe more complicated, I don't want it. I'm not the guy who happily builds raspberry pi control modules and such like that.

 

[dmtaylor]

You know, I always thought the kegland Pill tilt system was a silly thing. Just an unnecessary gadget, like wifi in a dishwasher.

But now I"m thinking, well, a refractometer is sixty bucks and so is a Pill.

Should I take the red pill or the blue pill, as Morpheus says?

The pill doesn't read accurately when yeast and hops are stuck to it in the fermenter.

If you want cheap & easy for your old eyes, I'd stick with a traditional hydrometer, and a $10 pair of reading glasses from Dollar Tree.

 

[Broken Crow]

I'm with @bike2brew in that at my age, it is difficult to exactly see where the hydrometer is floating.

My torn up axons make it difficult for me read any measurements even when I'm staring straight at them...what makes it easier is using my phone to take a picture so I can zoom in far enough the only thing I see is the line and the number next to it.
..that's why some of my posts have pictures of parts next to a ruler instead me trying to qoute measurements.....embarassing, but I often show the picture to my GF and have her read it for me. No shame in visual aids as ain't none of us gettin' any younger.

 

[worlddivides]

My torn up axons make it difficult for me read any measurements even when I'm staring straight at them...what makes it easier is using my phone to take a picture so I can zoom in far enough the only thing I see is the line and the number next to it.
..that's why some of my posts have pictures of parts next to a ruler instead me trying to qoute measurements.....embarassing, but I often show the picture to my GF and have her read it for me. No shame in visual aids as ain't none of us gettin' any younger.

That's exactly how I do it. I don't really think it has anything to do with age since I've always had trouble telling exactly where the hydrometer is at a glance. So I always take 2-5 photos of it, then zoom in on the different photos and determine where it is, then make any necessary temperature adjustments. For example, for my last brew, my hydrometer read 1.044, but it was taken at 82.4F, which gave it a temperature-corrected value of 1.046. After cooling down a sample to the 68-70F region, I checked with my refractometer and it also read 1.046. I don't know how people take photos from their refractometer, but photos of the hydrometer have been my norm for a long time now.

 

[Hoochin'Fool]

Does anyone sell reasonably priced hydrometers that cover a SHORT range? I'd love three different hydrometers, that didn't need to be so tall, but that covered:

• 0.995 to 1.035
• 1.045 to 1.085
• 1.090 to 1.130

and had decent space between the tick marks. Northern Brewer used to sell one that went from 1.000 to 1.070, but I don't see it any more, and google isn't giving me anything useful.

 

[Zadkiel]

I take a picture of my hydrometer with my phone and then zoom the picture.

I have very bad eyesight.

 

[BrewnWKopperKat]

Does anyone sell [...] hydrometers that cover a SHORT range?

F. H. Steinbart (link) has shorter range hydrometers: 0.098 – 1.020 SG; 1.000 – 1.070; & 1.060 – 1.130. Looks like they are also available in Brix and Plato scales. I bought the 0.098-1.020 one about a year ago.

IIRC, when this question came up about a year, there was another source for hydrometers in these range.

 

[kohalajohn]

I don't think it's "very bad eyesight". Everyone says that, so that means they are just damn hard to read.

You shouldn't have to take photos. That's a problem of the tool, not of you.

The refractometer is easy to read, but is never accurate out of the box, and needs to be calibrated.

Deep down I know I'll eventually break down and buy that Kegland RAPT Pill. I already have a Brewzilla gen 4 with RAPT interface and a rapt bluetooth mash thermometer.

RAPT is the Borg. Resistance is futile. Eventually I will be assimilated.

 

[MaxStout]

A few things:
Give the hydrometer a little spin when putting it in the sample jar of wort, to throw off any bubbles that may cling to the sides.
Before taking a reading with your refractometer, check the calibration with distilled or RO water at the instrument's cal temp (usually 60 or 68F). There should be a little screw you can turn to align it with 0 Brix.
For either instrument, be sure the wort is mixed well before drawing a sample, to reduce stratification.

 

[kohalajohn]

FH Steinbert makes a much better hygrometer, I'm sure.

But after shipping to Canada, it's actually cheaper to buy a Pill.

I see it like bbq thermometers. In the old days I'd check the doneness of a roast from time to time. But the time I poked in the thermometer would be before or after it was perfect. I just wouldn't know, being on the outside.

Then I got one of those bluetooth thermometers that you leave in the roast. It tells you in real time what's going on, so now my temps are perfect.

I think the Kegland Pill is like that.

 

[BongoYodeler]

I own two Pills but I have to agree with @dmtaylor they do have accuracy issues reading SG when yeast and hop debris are stuck to it. However, for me the Pill is invaluable in displaying the overall rate of fermentation, and also letting me know when FG is reached. But I still always check OG and FG with a hydrometer to make sure my Pill is in the same zip code.

 

[tracer bullet]

How long has your wort settled before your reading? I find that if I take a wort sample, I have to let it sit a while, 15 min or so, to settle some of the solids out of it. Afterwards, my hydrometer and refractometer agree a lot more closely to each other. Hydrometer basically stays the same but it's the refractometer that starts some ways apart and then comes in to match the longer the wort sits.

I'm talking a shot glass full over 15 minutes, so I don't think it's evaporation.

 

[Zadkiel]

I don't think it's "very bad eyesight". Everyone says that.

I promise you my situation is different. I have multiple medical conditions that affect my eyesight, one of which causes my optic nerve to swell up to 3 times it's normal size about once a decade, rendering me temporarily blind and in the process ripping out about half of the nerves in my eyes. if a normal person's vision is 4k, at this point I'm down to about 720p. And on top of that I have an insanely high lens strength and need 3 different glasses to wear for 3 different distances, with close range (reading) being at about +9.5. I am also type-1 diabetic and suffer from diabetic retinopathy on top.

So no, everyone doesn't say that.

I find taking a picture very helpful, and while I don't think others have as bad vision as me, I thought my extreme circumstances and workaround might be helpful to others who don't have to deal with my issues on a day to day basis and thus might not have come up with the same solutions as I use on a daily basis.

 

[kohalajohn]

I promise you my situation is different. I have multiple medical conditions that affect my eyesight, one of which causes my optic nerve to swell up to 3 times it's normal size about once a decade, rendering me temporarily blind and in the process ripping out about half of the nerves in my eyes. if a normal person's vision is 4k, at this point I'm down to about 720p. And on top of that I have an insanely high lens strength and need 3 different glasses to wear for 3 different distances, with close range (reading) being at about +9.5. I am also type-1 diabetic and suffer from diabetic retinopathy on top.

So no, everyone doesn't say that.

I find taking a picture very helpful, and while I don't think others have as bad vision as me, I thought my extreme circumstances and workaround might be helpful to others who don't have to deal with my issues on a day to day basis and thus might not have come up with the same solutions as I use on a daily basis.

Thanks for that. My eyesight is fine but maybe I'll try that photograph tip.

 

[pfabsits]

As an employee of a company that makes a digital refractometer, the biggest challenge we face is when the user uses water that is not purified. To the point that we buy DI water and re-package to be supplied with the meter. Overall, I would recommend buying a bottle of distilled water and use that to calibrate.

I plan on trying to see what the impact of using DI, RO, and tap water on a measurement reading. I would anticipate that the readings of a sugar solution will be lower when calibrating with tap over RO or DI. The rational is that the tap water is higher than 1.000 the reference point for DI. It is being forced to underestimate the reading.

Either way, the best recommendation is to purchase some distilled water and use that for calibration.

 

[Brewer Mike]

So, wouldn't the beer style have an effect on the refraction? i.e. a light lager vs a stout? My intuition says the color would effect the refraction.

 

[Yooper]

One thing that was hard for me was to accept "close enough". I'm a weirdly geeky perfectionist, and 20 years ago the difference between 1.048 and 1.052 would have bothered me. But really, a difference of .004 is 'close enough' as our equipment is not lab quality or that precise.

I do use a Tilt (like the Rapt pill, but I hate the Rapt stuff so don't use it, including the temperature probe), but it's not even that I need accuracy/precision now- just so I know the beer is done. It doesnt' really matter to me if it's finished at 1.012 or 1.016- it's 'close enough'. If it's finished, it's not going to get more finished so I'm good with it.

That said, I do know my wort correction factor, and my refractometer and hydrometer generally match at the end of the brew day. My Tilt is calibrated then too. And I really that what the refractometer reads and what the hydrometer reads are different but still useful data points. The data points just let me know if the beer is finished, and the approximate IBU:OG ratio. And really, the beer is great.

 

[Yooper]

So, wouldn't the beer style have an effect on the refraction? i.e. a light lager vs a stout? My intuition says the color would effect the refraction.

No.
Alcohol skews the refraction of light, so that can change the reading but the color doesn't matter at all.

 

[bwible]

And my Tilt doesn’t agree with either one.

 

[Broothru]

Pretty much agree with all the above comments. However, if you’re anal retentive (like me) about some things, and if you have some money to spend on accuracy, get an Anton-Parr EasyDens. Best toy ever.

Over the years I’ve lost track of the number or range of hydrometers that I’ve used/lost/broken. Also gone through three refractometers, including a Milwaukee electronic model. None was as accurate and easy to use, requiring less volume of liquid plus automatic temperature correction as the EasyDens.

Works on wine as well as other fermented liquids with the proper software app on your cell phone, if you’re into that kind of thing. You can store, sort, track and archive the progress of your fermentation, and display it in a variety of weights, volumes, density, etc., units of measurement. Built-in tools allow on-the-fly converting between Specific Gravity and Plato.

Pricey, but it’s an exceptional tool. Been using mine for almost three years without a hiccup. Small, compact, automatic, durable and accurate to 1/1,000 unit of SG (corrected for temperature) within 5 seconds on less than 10-15 ml of wort, must or finished beer/wine.

Mankind has progressed from counting fingers to abacus to pencil to adding machine to computers. I went from “looks about right” to hydrometers to refractometers to electronic measurement with Anton-Parr’s EasyDens, and I ain’t goin’ back.

 

[pfabsits]

So, wouldn't the beer style have an effect on the refraction? i.e. a light lager vs a stout? My intuition says the color would effect the refraction.

All refractometers are dependent on the refraction of light which is based on the refractive index (RI) of the solution being measured. Manufacturers of digital refractometers make multiple variations of the same product. When RI is converted to Brix it is based on a sucrose solution according the ICUMSA (International Commission for Uniform Methods of Sugar Analysis) published data. The meter is designed to display a Brix reading and assumes that the solution is sucrose and water. Not with some other diluent such as alcohol. That would yield a different result.

RI can be converted to other units of measure such as glycol for those that need to know the freezing point of the glycol:water mix used in cooling lines.

It is important to note that glycol can be placed on a Brix refractometer and displays the reading as Brix (as if it was a sucrose solution) and a sucrose solution can be placed on a glycol refractometer and glycol reading will be displayed. The meter does not know what solution is being placed on the prism but will report results based on the RI value of it.

The digital refractometer that we manufacturer uses a yellow LED (589 nm) as a light source.It is an interesting question as to whether color will be an interference. It is not measuring absorbance but the refraction of light. With absorbance a solution that is blue in color would be adsorbed since it is a complimentary color to the yellow wavelength. I am just not sure about the refraction part but believe that is not color dependent.

What I can say is that the digital refractometer is used in many industries including wine (Before and after crush), milk, and other substances. I have been looking at the amount of sugar found in plants. In the hydroponic market they are using refractometers and I am trying to understand the application and how to do the sample prep. A hydroponic retailer stated that a grower can tell when the cannabis flower is ready to be harvested by the sugar levels. The sugar levels will increase as the flower materues and decreases when at its' peak. So far I have been able to get a drop out of a tomato leave and had a reading in-line with published data. The solution was green in color.

 

[pfabsits]

Pretty much agree with all the above comments. However, if you’re anal retentive (like me) about some things, and if you have some money to spend on accuracy, get an Anton-Parr EasyDens. Best toy ever.

Over the years I’ve lost track of the number or range of hydrometers that I’ve used/lost/broken. Also gone through three refractometers, including a Milwaukee electronic model. None was as accurate and easy to use, requiring less volume of liquid plus automatic temperature correction as the EasyDens.

Works on wine as well as other fermented liquids with the proper software app on your cell phone, if you’re into that kind of thing. You can store, sort, track and archive the progress of your fermentation, and display it in a variety of weights, volumes, density, etc., units of measurement. Built-in tools allow on-the-fly converting between Specific Gravity and Plato.

Pricey, but it’s an exceptional tool. Been using mine for almost three years without a hiccup. Small, compact, automatic, durable and accurate to 1/1,000 unit of SG (corrected for temperature) within 5 seconds on less than 10-15 ml of wort, must or finished beer/wine.

Mankind has progressed from counting fingers to abacus to pencil to adding machine to computers. I went from “looks about right” to hydrometers to refractometers to electronic measurement with Anton-Parr’s EasyDens, and I ain’t goin’ back.

I will have to look into the AP meter. Maybe the technology is something we can look into as well.

 

[Whisky River]

One thing that was hard for me was to accept "close enough". I'm a weirdly geeky perfectionist, and 20 years ago the difference between 1.048 and 1.052 would have bothered me. But really, a difference of .004 is 'close enough' as our equipment is not lab quality or that precise.

I do use a Tilt (like the Rapt pill, but I hate the Rapt stuff so don't use it, including the temperature probe), but it's not even that I need accuracy/precision now- just so I know the beer is done. It doesnt' really matter to me if it's finished at 1.012 or 1.016- it's 'close enough'. If it's finished, it's not going to get more finished so I'm good with it.

That said, I do know my wort correction factor, and my refractometer and hydrometer generally match at the end of the brew day. My Tilt is calibrated then too. And I really that what the refractometer reads and what the hydrometer reads are different but still useful data points. The data points just let me know if the beer is finished, and the approximate IBU:OG ratio. And really, the beer is great.

(I too hate the rapt environment)

One thing I came to learn about myself is that I’m ok with “close enough” because I can always improve if I know where I’m at, but I can’t stand not knowing if my measurements are reliable. I’m fine with getting 1050 on a 1052 target (not really, but I can stand stand it) but it’s incredibly frustrating to get one form of measurement that says I got 1048 and one that says 1052. I tried every device I could and at the end I realized that consistency and technique in using the tool is at least as important as how “accurate” the tool is. If my procedure for pulling a sample isn’t consistent I can still get 2 different readings from the Easydens and that’s about as reliable a measurement device as I can imagine short of true lab grade equipment. I buy almost all my gear used and got a deal on several tilts and now I use 2 tilts in the fermenter because Ive got them lying around and having just one and not being able to trust the measurements because it might be hung up on something drives me nuts!
So beware of thinking there’s something out there that will give you real certainty, it’s elusive and the path to find it has lots of tempting but probably unnecessary gear on it.

 

[kohalajohn]

I own two Pills but I have to agree with @dmtaylor they do have accuracy issues reading SG when yeast and hop debris are stuck to it. However, for me the Pill is invaluable in displaying the overall rate of fermentation, and also letting me know when FG is reached. But I still always check OG and FG with a hydrometer to make sure my Pill is in the same zip code.

Yes, it makes sense that in full krausen, yeast and foam and hop debris could pile onto the Pill and affect accuracy.

But wouldn't this mainly be a problem only in mid fermentation, meaning full krausen, and not near the start or finish? Since it's the start and finish I care about, a mid ferment error would not be very important to me.

Also I read that the new Pill software will scan through the hundreds of readings and throw out what are obvious outliers.

Still considering a Pill for me. I get that it's not for everyone.

 

[Yooper]

Yes, it makes sense that in full krausen, yeast and foam and hop debris could pile onto the Pill and affect accuracy.

But wouldn't this mainly be a problem only in mid fermentation, meaning full krausen, and not near the start or finish? Since it's the start and finish I care about, a mid ferment error would not be very important to me.

Also I read that the new Pill software will scan through the hundreds of readings and throw out what are obvious outliers.

Still considering a Pill for me. I get that it's not for everyone.

Well, yes, but.....the krausen sticks to the device and weighs it down. That affects accuracy quite a bit. If the hops debris and krausen just disappeared when the krausen falls, it wouldn't matter.

I have a Tilt, and I love it and once it a while some hops from dryhopping drop it down and it gets inaccurate, but usually it's just fine and close enough!

 

[Broothru]

Yes, it makes sense that in full krausen, yeast and foam and hop debris could pile onto the Pill and affect accuracy.

But wouldn't this mainly be a problem only in mid fermentation, meaning full krausen, and not near the start or finish? Since it's the start and finish I care about, a mid ferment error would not be very important to me.

Also I read that the new Pill software will scan through the hundreds of readings and throw out what are obvious outliers.

Still considering a Pill for me. I get that it's not for everyone.

The accuracy of EasyDens data can definitely be inaccurate if the sample is cloudy or or not degassed, just as readings can be inaccurate in refractometers (if optically cloudy, interfering with spectral refraction) or CO2 bubbles adhering to the bulb of a hydrometer.

If my O.G. sample pre-pitch or high krausen is cloudy, I strain it through a paper coffee filter. If there is a lot of gas present, I vigorously stir the sample briefly to disperse the CO2, just like I did when using a refractometer or a hydrometer.

When I first got the EasyDens, I took parallel readings with hydrometers, refractometers and the Anton-Parr, both clear and unsettled. Multiple readings of the same sample on the same device often showed different values (generally small, not consistent) on the refractometers and hydrometers, but not the Anton-Parr.

The variance between unsettled/gassed values is smaller (or zero) with EasyDens. Carefully cleared and degassed samples measured on all devices are generally the same, although muddled samples diverge less from clear samples with EasyDens.

So, in general the EasyDens appears to be more accurate in measuring cloudy samples than the other devices. Plus, its ease of use, consistency, small sample size requirement, speed of use, automatic temperature compensation result in a very useful tool.

 

[kohalajohn]

Well, yes, but.....the krausen sticks to the device and weighs it down. That affects accuracy quite a bit. If the hops debris and krausen just disappeared when the krausen falls, it wouldn't matter.

I have a Tilt, and I love it and once it a while some hops from dryhopping drop it down and it gets inaccurate, but usually it's just fine and close enough!

Sigh. Nothing is perfect.

I can see why people just stick with a hydrometer. It does work and is simple.

There was a post earlier about an easier to read hydrometer. That certainly is worry free.

https://fhsteinbart.com/product/specific-gravity-range-precision-hydrometer-1000-1070-sg/