refractometer / hydrometer issues

[Lauritsen]

I think I have FINALLY found a significant issue regarding the issue of difference between hydrometer and refractometer readings.

If you have tried both you might see they give you different readings when measuring SG/Brix in must.

I have read up on in alot as I like to be accurate, but it seems most people just agree that there is and will be a bit of a difference between the two readings and people live with it - though its a sade inaccurate life to live

I used http://www.brewersfriend.com/brix-converter/
but no, my readings does NOT match what the calculater(s) say.

My refractometer sais 10.8, but hydrometer sais 1.046
According to the calculator, the hydrometer SHOULD say 1.043 when measuring 10.8 brix

... and then I had an idea; :smack: YOU NEED TO CALIBRATE YOUR HYDROMETER.

Whaaaaaaat? Calibrate hydrometer? You ask.

Yes!!

Hydrometer measures density of fluids. People assume water is 0 (1.000). Well, yes PURE water. BUT you probably do NOT use PURE water do you??? Noooo......

Where I live the tab water is bone hard. This is due to minerals in the water.

First, You need to hydrometer check the water you want to mix in.
Mine said 1.003 - no sugar. Its just because its hard water. Try adding table salt to the water and see what happends

OK - I now mix water in the juice - AND WAIT. You cannot get a correct reading the first few minutes. This is because there will be a load of air in the must now. If you have seen the show - I think its called "myth busted" - the ugly red haired guy was swimming in a swimming pool where they made lots of air bubbles under him and then the ugly guy with the hat and fake mustage measured what happened. He was sinking!

You would think lots of air in the must would drive UP the hydrometer - but its opposite. So, wait a few minutes.

As mentioned above the hydrometer measured 1.046 and the refractometer 10.8
I now use my calculator to deduct 1.046 with the hard water measurement of 1.003. I get 1.043. Do you agree?

Using the brix/Gravity calculater, it now ads up..:rockin:


Voila - one of the biggest homebrew problems solved.
I await a nobelprize for this!



(can I get a "like" for this)

 

[Yooper]

http://byo.com/hops/item/1313-refractometers

 

[jddevinn]

http://www.brewersfriend.com/brix-converter/[/url]
but no, my readings does NOT match what the calculater(s) say.

My refractometer sais 10.8, but hydrometer sais 1.046
According to the calculator, the hydrometer SHOULD say 1.043 when measuring 10.8 brix

The converting formula uses a constant that must be empirically derived for each beer/wine. For "house" beers I have calculated this and just use a refractometer, for "new" or developing recipes a hydrometer is required to determine the actual gravity.

Remember a refractometer is measuring light refraction, which changes with sugar content. A hydrometer is measuring specific gravity, which changes with sugar and alcohol content.

 

[Firewalker11]

Thanks Yooper for that link, this is what I did when I started by adjusting my refractometer to my wort style. I only use my hydrometer to verify my instant refractometer readings now.

I found an interesting issue with my refractometer last weekend, when using an LED flashlight to get good contrast, I had to point the beam horizontally at the tip of the refractometer to get a clear line. Strange huh?

 

[eluterio]

Had a good chuckle or two over the myth busters comments. Yes I watch the show what guys doesn't like seeing things blown up.

 

[Dutch_Food_Geek]

Of simply do everything on your refractometer... Theres no need whatsoever to use both... So no calculations... And they're both just as inaccurate...

 

[gregbathurst]

Some cheap homebrew hydrometers are wildly inaccurate. They may be correct at 0.00 but still incorrect at other readings. For some reason they always exaggerate the amount of sugar. you can buy certified hydrometers but they are expensive, there are good quality non-certified ones as well. The ones that are given out free with homebrew kits are not great. It doesn't really matter for monitoring the progress of fermentation but if you want an accurate OG it does matter, especially if trying to measure ripeness of fruit. If you can compare your hydrometer to a good quality hydrometer or refractometer that is a good way to calibrate it.

 

[Firewalker11]

I'm not really sure I could qualify that statement Greg, of the sub $6 hydrometers I have purchased, they all seem to be spot on in 65 degree distilled water and at 1.100 by sugar concentration.

 

[gregbathurst]

If you are happy with your hydrometer that is fine, they are mainly for relative measurements anyway. I think it is better to compare to a professional quality instrument rather than making up your own solution. If you think a $6 hydrometer is as accurate as a $40 hydrometer I admire your optimism, but I would rather pay a bit more to be sure.

 

[Firewalker11]

If you are happy with your hydrometer that is fine, they are mainly for relative measurements anyway. I think it is better to compare to a professional quality instrument rather than making up your own solution. If you think a $6 hydrometer is as accurate as a $40 hydrometer I admire your optimism, but I would rather pay a bit more to be sure.

I'll take the bait:

I work in a winery a few times a week and work with the chemist, the owner has all the delightful calibrated equipment there to work with.

That said, the overall deviance between a $6 hydrometer (that reads 1.000 in distilled water and 1.100 in a sugar/distilled water solution of 32.6 ounces of cane sugar per gallon of water) and a $25-$90 hydrometer with a NIST traceable certificate of calibrations is less than 1%. This seems to be true of all the hydrometers I have as it is instantly obvious that if a hydrometer is spot on at 1.000 gravity, it will likely be accurate at 1.100 as well... In my experience.

I just don't want n00b3 thinking they need a $40 hydrometer when the relative accuracy of an inexpensive hydrometer will work fine.

 

[GHBWNY]

Hydrometer.

My S-I-L and I often split ingred's to brew the same recipe by basically the same process. Our respective OGs have always been similar, but his FG has always been much higher than the target FG (and mine). But his beer tasted great (like mine). Each time we'd go back over his process: How was your mash temp? aeration? yeast? pitching temp? rehydrating? ferm temp? agitating and moving to a warmer spot? re-pitching? blah, blah, and could never find anything wrong in the process. I began to wonder if his hydro could be that far off, except it measured OG just fine. And then I discovered he didn't even own a hydro! He was using a refractometer to measure both OG and FG. Big aha! moment. After I told him that alcohol will skew a refract's FG reading, he recalculated his readings and found they were spot-on the target FGs. And then he went out and bought a hydro.

 

[gregbathurst]

I'll take the bait:

I work in a winery a few times a week and work with the chemist, the owner has all the delightful calibrated equipment there to work with.

That said, the overall deviance between a $6 hydrometer (that reads 1.000 in distilled water and 1.100 in a sugar/distilled water solution of 32.6 ounces of cane sugar per gallon of water) and a $25-$90 hydrometer with a NIST traceable certificate of calibrations is less than 1%. This seems to be true of all the hydrometers I have as it is instantly obvious that if a hydrometer is spot on at 1.000 gravity, it will likely be accurate at 1.100 as well... In my experience.

I just don't want n00b3 thinking they need a $40 hydrometer when the relative accuracy of an inexpensive hydrometer will work fine.

Possibly I have just had a bad experience and cheap hydrometers are accurate these days. My first hydrometer (cheap) was accurate at 1.000 but not at any other reading. I tried to make a reference solution and it seemed fine but when I compared it to a winemaker's hydrometer it was way out. I think for most people like me making a proper reference solution will not be reliable, much easier to just compare to an accurate instrument for calibration. I personally don't think much care will have gone into the production of a $6 hydrometer, but they will be fine for beginners especially if calibrated against a reliable hydrometer. If cheap hydrometers were as good as the expensive ones, why would professionals spend so much on the proper equipment? This is all just my opinion of course, I just think people should be aware there may sometimes be issues with cheap hydrometers.