hydrometers calibrations and temperatures

[ibglowin]

They doing any (oil) Fracking in your neck of the woods! Thats pretty low, but not all that uncommon really. Do you have some distilled water to try and see what it reads just to see if it comes in closer to 7?

 

[MalvinaScordaad]

There seems to be some misconceptions that have been posted here about the Calibration and use of a hydrometer in Wine Making. Contrary to what has been said here the hydrometer is probably one of the most useful tools in a Wine Maker has in his tool kit.

On the subject of temperature. When you are testing Brix after Crush the Must Temperature and the readings on the Hydrometer come into play. But the differences in Brix between 55 degrees and 70 degrees are not that different. What is important, actually very important, is learning the sugar content of the Must for 2 major reasons. Whether to add sugar or add water or to leave it alone. Also it is important knowing your Yeasts’s fermentation abilities as it relates to Brix and to make initial adjustments if necessary with a Must too high or too low in Brix level. This is critical. Yes you can attempt to use it at that time to estimate your alcohol content when fermentation is complete but if you research Brix charts and ABV you will discover that an accurate prediction is not reality.

As far as Calibration goes it makes no sense to think you are accomplishing anything worthwhile calibrating with distilled water attempting to come to a conclusion of calibration at zero brix. First, inexpensive hydrometers are not always accurate. But even if they are, a reading at zero brix in distilled water is a waste of time. The reading and calibration you want is at 25 brix. That is where most of the errors show up. And for the reasons stated above a reading of 23 or 25 may change a winemaker’s decision whether to add water or add sugar. That is why testing and determining a calibrating factor for your hydrometer at 25 Brix is what you need to do especially when using the garden variety hydrometer.

There are two ways to calibrate your hydrometer. One is to buy a Laboratory Standard Calibrated Hydrometer (about 50 dollars) and use that against your other inexpensive one and determine a plus or minus factor to use prior to fermentation. This way you can keep your Lab Standard Hydrometer safe and use the inexpensive one. The other way is to purchase 25 brix lab standard solution. Then you can determine the error at 25 brix in your hydrometer and record a correction factor to use.

The use of the Hydrometer during fermentation is also important for a few reasons. While total accuracy is less important, you will want to have a good idea of brix level at various stages to determine nutrient addition staging and tracking fermentation progress. One example could be avoiding adding any product with DAP in the Must below 10 brix another could be determining the fermentation speed and the need to raise or lower heat, or add a non DAP containing nutrient in later stages of fermentation. A dividing by half of Brix level in 24 hours in fermentations below 8 brix demonstrates a healthy fermentation. Less than that indicates a slowing down that needs to be watched carefully. When reaching 5 brix it is a good idea to use a small scale hydrometer with a Plus 5 –Negative 5 scale. It is much easier to read. At this time you can determine if your Brix is low enough ( 2 brix of lower) to consider adding ML Bacteria if you wish before you press. Also it will be able to read below zero as fermentation completes. However it is no indicator of a finished fermentation. Alcohol Content and other factors affect the reading below zero. So it is quite possible to read a minus 1 and still have remaining sugar to ferment. A better way through observation after pressing is to observe any bubble activity in a carboy with the wine held at 70-75 degrees for a few weeks. Of course if you are doing a Malolactic Fermentation both would be happening at the same time so it would be hard to tell. Another way is to employ a Clinitest. It will give you a very good idea of residual sugar in your wine so when testing for Malic Acid content you can test for residual sugar as well.

One thing don’t bother testing distilled water ph since it does not have any ions for the PH Meter to work with.

Hopes all of this helps you out Shane.

 

[ibglowin]

Freshly distilled water should have a pH of 7.0. However, interaction with the atmosphere allows carbon dioxide to dissolve into it, forming carbonic acid. As a result, agitating the water or allowing it to sit for a while will leave you with an aqueous solution that drifts down in pH. Because there are no natural buffers in distilled water, the pH can go down as low as 5.0.

One thing don’t bother testing distilled water ph since it does not have any ions for the PH Meter to work with.

 

[MalvinaScordaad]

Freshly distilled water should have a pH of 7.0. However, interaction with the atmosphere allows carbon dioxide to dissolve into it, forming carbonic acid. As a result, agitating the water or allowing it to sit for a while will leave you with an aqueous solution that drifts down in pH. Because there are no natural buffers in distilled water, the pH can go down as low as 5.0.

Whether it is dissolved Co2, the lack of Ions, or the ability of type of probe, there is no value in using distilled water to check the calibration of a PH Meter. It seems the problem is greater than just carbonic acid.

From Orion Research Inc.
Conventional pH electrodes, which are designed to function in high-conductivity solutions, show slow and erratic response in pure water samples such as acid precipitation. Increasing conductivity without shifting pH solves the measurement problem. This method correctly measures pH in low conductivity solutions, using a Ross combination pH electrode, after the addition of a small amount of potassium chloride (KCl) solution to the sample. The Ross electrode, with its unique internal redox system, is chosen since it eliminates problems associated with temperature and because the precision and accuracy of data obtained in preliminary testing with it were comparable to those obtained with the standard hydrogen electrode. KCl addition to samples does not alter the pH significantly.

 

[djrockinsteve]

I do not calibrate or check it myself. I take a reading and record it. Done.

 

[BobF]

Same here Steve. I find the hydro to be invaluable. I just don't think ABV determination with a hydro is accurate.

Long live hydrometers!

 

[Deezil]

As far as Calibration goes it makes no sense to think you are accomplishing anything worthwhile calibrating with distilled water attempting to come to a conclusion of calibration at zero brix. First, inexpensive hydrometers are not always accurate. But even if they are, a reading at zero brix in distilled water is a waste of time (1). The reading and calibration you want is at 25 brix (2). That is where most of the errors show up. And for the reasons stated above a reading of 23 or 25 may change a winemaker’s decision whether to add water or add sugar. That is why testing and determining a calibrating factor for your hydrometer at 25 Brix is what you need to do especially when using the garden variety hydrometer.

There are two ways to calibrate your hydrometer. One is to buy a Laboratory Standard Calibrated Hydrometer (about 50 dollars) (3) and use that against your other inexpensive one and determine a plus or minus factor to use prior to fermentation. This way you can keep your Lab Standard Hydrometer safe and use the inexpensive one. The other way is to purchase 25 brix lab standard solution. Then you can determine the error at 25 brix in your hydrometer and record a correction factor to use.

1 - I would just like to see proof. (proof: documentation from a college or 'accredited' wine association... random websites, i have a hard time believing all the time.. i take most everything with a grain of salt)

2 - First time i've heard this.. Hence wanting to see proof of #1

3 - I looked into these... and even the directions that come with them, specifically mention using distilled water to make sure the hydrometer is accurate. I looked at several different types (those used in oil, for example), through several different manufacturers, on several different websites. And they all said the same thing.

The theory of what you said, sounds alright.. But proof would seal the deal. Everything i've read thusfar, speaks of distilled water to calibrate at for 1.000

 

[MalvinaScordaad]

If you want proof then that is very easy test 3 inexpensive hydrometers at O brix and then at 25 brix. The major differences occur at the top of the scale not at the bottom. And those errors are more significant to the winemaker when making amelioration or chaptalization decisions. Documentation is sometimes the best when you discover it for yourself.

 

[Deezil]

If you want proof then that is very easy test 3 inexpensive hydrometers at O brix and then at 25 brix. The major differences occur at the top of the scale not at the bottom. And those errors are more significant to the winemaker when making amelioration or chaptalization decisions. Documentation is sometimes the best when you discover it for yourself.

The only thing that would show me is that the amounts that inexpensive hydrometers are off at 0 Brix, would then be compounded at 25 Brix. It wouldnt make measuring hydrometers with distilled water obsolete.
Edit: So i thought about this a little more... And honestly, would it compound? Or would it be off by the same degree either way? Talking about TDS in a liquid, my heads having a hard time wrapping around it because i cant actually *see it*

So you're right, in that the major differences will be at the top-end of the scale. That'll i'll give you. But it also wasnt what i wanted to see proof of.

You said measuring inaccuracies in inexpensive hydrometers is 'a waste of time' using distilled water. So far, the evidence suggests that clearly its not. The manufacturers, the vendors, the customers - they all say the same thing...

I guess there's always 'two ways to skin a cat'

 

[MalvinaScordaad]

Skin a cat anyway you wish but what is really important to the wine maker is using the accuracy of the reading at the beginning of the fermentation. What difference does it really make at 0 or minus 1 or 2 when that reading is more effected by Alcohol Content than actual remaining sugar content. What is important at the beginning is Sugar Content. At the end of fermentation a small scale hydrometer is more useful in seeing 24 hour changes in levels to determine continued fermentation. But using the Hydrometer to determine actual completion of all sugar fermentation is not really possible. Whether it is calibrated at zero or not. Why bother calibrating at zero with distilled water when you really are interested in the calibration at 25 Brix when it matters. It seems pretty obvious your are calibrating at the wrong end of the scale in any case.

As to your question the answer is no. They are off much more at 25 brix than at zero. And Manufactures take the easy route here and tell you to test at Zero. As far as customers are concerned, many here, have never heard of a Lab Standard Calibrated Hydrometer or for that matter 25 Brix lab standard solution used primarily to adjust Refractometers. If we used your argument why not adjust your Refractometer with distilled water. It doesn't work that way. That's why.

 

[Deezil]

Skin a cat anyway you wish but what is really important to the wine maker is using the accuracy of the reading at the beginning of the fermentation. What difference does it really make at 0 or minus 1 or 2 when that reading is more effected by Alcohol Content than actual remaining sugar content. What is important at the beginning is Sugar Content.

I'll skin a cat while it's still screaming if i feel like it, have you no fear in that.

You stress the importance of the accuracy in the initial reading, but downplay the importance of a final reading. Hydrometers measure more than just the sugar in the solution - which im sure we both know because you've also pointed out. So the accuracy you stress in the beginning, is theoretically thrown off just like your final readings, albeit by a different cause.

Alcohol content, however, affects a hydrometer reading in the opposite way than the sugar content would because alcohol is less dense than water - this would make it sink farther & read a lower number (This opposite-reaction could possibly negate some/all of the inaccuracy in a hydrometer, but that's only theoretical and not something we could readily test). While, obviously, sugar would be adding more TDS to the liquid therefor making it more dense - raising the hydrometer.

Why bother calibrating at zero with distilled water when you really are interested in the calibration at 25 Brix when it matters. It seems pretty obvious your are calibrating at the wrong end of the scale in any case.

Honestly, you've left me scratching my head here. Obviously its not very obvious, or we wouldn't be having this conversation would we?

As to your question the answer is no. They are off much more at 25 brix than at zero. And Manufactures take the easy route here and tell you to test at Zero. As far as customers are concerned, many here, have never heard of a Lab Standard Calibrated Hydrometer or for that matter 25 Brix lab standard solution used primarily to adjust Refractometers.

So then you're saying the inaccuracy at 0Brix is compounded when you reach 25Brix. By what degree, who knows.. But compounded nonetheless.

If we used your argument why not adjust your Refractometer with distilled water. It doesn't work that way. That's why.

If you dont use distilled water, what do you use? I could see an argument for 2-point calibration (distilled water & 25Brix) over a single-point... But lemme guess, you only use a 25 Brix solution for your refractometer too?

 

[altavino]

In the oenology program I attended at Curtin University , we were taught to calibrate hydrometers at 25 brix . using a solution of 250 grams of sugar measured on a digital scale made to a litre of water .

one thing to keep in mind is that hydrometers are not absolutely accurate as others have stated , neither is a refractometer . its hard to be absolutely accurate with a hyper complex solution such as must. (hyper complex meaning there are many ingredients other that sugar and water and many of those same ingredients are in a state of chemical transition or flux)

Zac put it best when he said " a hydrometer is a sundial not an atomic clock"

you don't need it to be absolutely accurate , otherwise if you did you'd be pulling samples and running off to a mass spectrometer and gas chromatograph every day. hydrometers and refractometers are feild tools which are "close enough" for our needs.

anyway one of my profs explained measuring brix as being most important preferment so you can make adjustments , after that you are just tracking the dropping movement of the sugars being consumed to ensure that you are not dealing with a stuck ferment. then when you think its dry and the hydrometer indicates this. he said to run a confirmation test to be sure such as a clintest. probably overkill for a home winemaker but the point is commercially you run a second test to confirm dryness .
often you also send a sample to a lab for a full panel , which tests for a range of things , including residual sugar, such is the lack of trust in the final reading, which would indicate clibration is best done at the start , and 25 brix is closer to that end.


here is a good set of fermentation calculators which may help your fermentations

http://vinoenology.com/calculators/fermentation/

 

[MalvinaScordaad]

I'll skin a cat while it's still screaming if i feel like it, have you no fear in that.

You stress the importance of the accuracy in the initial reading, but downplay the importance of a final reading. Hydrometers measure more than just the sugar in the solution - which im sure we both know because you've also pointed out. So the accuracy you stress in the beginning, is theoretically thrown off just like your final readings, albeit by a different cause.

Alcohol content, however, affects a hydrometer reading in the opposite way than the sugar content would because alcohol is less dense than water - this would make it sink farther & read a lower number (This opposite-reaction could possibly negate some/all of the inaccuracy in a hydrometer, but that's only theoretical and not something we could readily test). While, obviously, sugar would be adding more TDS to the liquid therefor making it more dense - raising the hydrometer.



Honestly, you've left me scratching my head here. Obviously its not very obvious, or we wouldn't be having this conversation would we?



So then you're saying the inaccuracy at 0Brix is compounded when you reach 25Brix. By what degree, who knows.. But compounded nonetheless.



If you dont use distilled water, what do you use? I could see an argument for 2-point calibration (distilled water & 25Brix) over a single-point... But lemme guess, you only use a 25 Brix solution for your refractometer too?

While you are skinning that cat again , yes the alcohol does affect the readings as it increases in the must but what is important is the reading when there is no alcohol present. That is the most important reading. As Altavino has just said after that the reading is tracking the reduction of sugar. You are not tracking the increasing alcohol. And when you get to close to the end of the sugar depletion the Alcohol effect has more bearing on the reading. That inaccuracy in the hydrometer's ability,due to other components in the wine, to measure a completed fermentation of any remaining sugar is why you can be Dry at minus .5 or not dry at minus 1.

But you make the case of calibrating at the point where you can't trust the reading you are trying to make and which, while you might want to know when the sugar is no longer present, the device you want to use is incapablle of actully determinging that in the first place.

Common sense not a College Class tells you to calibrate a tool to make a reading where that reading is most important. Not at the opposite end of the scale where the error can only be compounded. That is the obvious part of the discussion.

On practical level you, since Altivino has just provided you with a formula to make a 25 brix solution, can test your own hydrometers. You can still test at 0 with distilled water only to see if they read correctly at that end of the scale. Unlike the serious importance of accuracy in the 26 to 22 range where decisions have to be made, it matters very little at the opposite end since in the range of 0 to minus 2 you can still have unfermented sugar and an incomplete yet still active fermentation. In my experience I have 4 hydrometers that cost less than 20 dollars and 1 that is a Certified Lab Standard Hydrometer. Only the lab standard reads correctly at 25 brix. The others read anywhere from 22 to 27. All of them read 0 in distilled water.

Where a Home wine maker and a Commercial winemaker part company could be another discussion. As to overkill, and not relying on the Sun Dial, the 35 dollar Clinitest kit is not really overkill in my mind if you are truly interested in determining a completed sugar fermentation. One thing is for sure though as the Professor said, the hydrometer is not the answer for that no matter how much distilled water you use.

 

[BobF]

Mal (can I call you that?),

I agree with you that the upper end is the best place to calibrate. IIRC, Luc posted a link to an article some time ago regarding hydro calibration and varying degrees of accuracy amongst the common hydrometers sold for home winemaking.

The best reason I can think of for calibrating (standardizing?) at the starting range is that the errors are likely not linear. At the very least, it would incorrect to assume a constant offset without verifying.

Anyone interested in this topic would be doing well to find/read Luc's article.

Even standardized at 25 brix, there is still a large assumption being made - that fermentable sugar is the only dissolved solid contributing to the reading. I'm not saying one shouldn't try to be as accurate as possible - this is, after all, an industry standard assumption. I'm simply trying to dispel the notion that a hydrometer reading will nail things to within a gnats *** width.

I feel the time I would spend separating fly dung from pepper would be better spent elsewhere in the process

 

[MalvinaScordaad]

Yes dear you can call me Mal.

Yes I think that the errors are not linear and assuming a constant offset would be a leap of faith. Furthermore you are correct about the readings at the crush. There are a lot of factors that can affect the results. There are a few methods to minimize that. One is settled juice but that is not perfect as some sugars are contained in the grapes and not fully dissolved. I have also noticed that there can be a considerable bump up in Brix after Cold Soak and during lag phase. But you have to make a decision at some point if you plan on taking any external action. At least trusting the hydrometer to be accurate to itself is a good starting point.

The original poster was expressing considerable frustration with trying to use the hydrometer to determine the end of fermentation. He said ,"damn really. Thats brutal. how do they expect us to know when our stuff is done?! .. I think that is funny. They don't expect anything Shane. As a Winemaker it is up to you to figure it out. The best advice to give you Shane, failing to use a Clinitest, is to keep the hydrometer in the drawer after the level stops dropping, store your wine warm for 3-4 weeks at 75 degrees and observe any activity in the neck of the carboy.

 

[whackfol]

Wow, 30 posts in four days -- I had to read them all. I'm from the school that no matter how calibrated, the hydrometer is only a tool to gauge and adjust the starting Brix and monitor fermentation. (During fermentation I'm more concerned with the temperature and with the timing of my additions). In the end, I use the Clinitest to measure residual sugar. The level of accuracy I require is more than offset by the variability of the sugar vs non sugar solids in the must and the variability of PA estimates based on beginning BRIX.

As to the hydrometer, they are used heavily at my place of work. I had a quick conversation with our head scientist about the use and calibration of hydrometers. I don't pretend that I fully understand what was said. What I do know is he busted many of my assumptions and methodologies. For instance, I consider "pure water" as distilled or deionized. In his world there is a spec for water that includes conductivity, maximums of chlorides, silicas, sodium and other minerals. Temperature is a big issue in measurement of BRIX. However, how many of us have a calibrated thermometer? I have a few "good quality" thermometers purchased from lab supply stores. None is within 3/10 of a degree C. He sends his hydrometers out to be calibrated to a NIST standard. Typically this includes different test methodologies. In house he uses three point calibration (none zero) with non-sugar standards approved by NIST. He would never use a single point reference for hydrometers, pH meters and many other items in his lab. So far we have discussed the viscosity of the liquid, I learned that the barometric pressure will affect a reading.

For my purpose (wine making) he recommended calibrating 1) using distilled water for zero, 2) using a sugar mixture that is in the 50% range of my hydrometer and 3) one that is 90% of my hydrometer scale. His rationale is that the paper scale in hydrometers may not be accurate across the entire scale and shock to the instrument can jar the paper scale. Above all, he recommended calibrating my thermometer and taking careful measurement of temperature for temperature correction.

 

[shanek17]

okay so I tried keeping up with this thread but you guys went way over my head with hydrometers. I ended up going out and getting a new one from the same store but this one is a little different , this one is calibrated to 60F instead of 68F. I actually have a question though about how to properly read it . The instructions look confusing so Im taking a picture now to show you all. So the picture says reading below meniscus , which makes me think they are saying to take the reading below the water climbing up around the hydrometer. But if that is true then why in the picture do they show it being measured at 1010?

so I have posted both instructions for my 2 hydrometers, the first picture is for the hydro that is calibrated to 60F and the second instructions with the green water are from the 68F hydro. Its just weird that they say to read either above or below.

 

[Runningwolf]

Always read below. The actual readings would be 1.000 or 1.010 It will save you a lot of grief later to use the decimal point and expand out 3 digits. It will also help us understand where your readings are at as you ask questions. This was something I also had to get use to and most beginners do. Heck there are even people who have been making wine for years and don't even know what a hydrometer looks like. Keep asking and we'll walk you through anything.

 

[JordanPond]

The most important practice would be to be concistent when taking a reading. Always read above or always read below. That prevents you from introducing an error.

 

[BobF]

I also have hydros with different temps and instructions for reading. I always follow the instructions specific to the individual hydrometer.