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Adjusting Hydrometer for Temperature and Dodginess

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cremmerson

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Just seeking some confirmation.

I tested my dodgy Coopers hydrometer and found it to be four points under for water (so 996 instead of 1000).

I also have some variability in my wort as it proceeds apace.

However, I want to have some confidence in the end ABV.

SO - is it appropriate for me to:
(1) take a hydro reading;
(2) add four points for a corrected reading, then
(3) adjust corrected reading for wort temperature (http://www.brewersfriend.com/hydrometer-temp/); and
(4) plug adjusted numbers into the formula below to calculate ABV?

ABV = (OG-FG) / 7.46 + 0.5

This makes sense to me as it is correcting for dodginess and "normalising" for temperature, but it would be nice to confirm.

Thanks all.
 

Yob

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5. Write an email to Coopers and get them to replace it. Don't let them get away with it.

But yes to the question, just adjust your readings...
 

thylacine

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cremmerson said:
Just seeking some confirmation.

I tested my dodgy Coopers hydrometer and found it to be four points under for water (so 996 instead of 1000).

I also have some variability in my wort as it proceeds apace.

However, I want to have some confidence in the end ABV.

SO - is it appropriate for me to:
(1) take a hydro reading;
(2) add four points for a corrected reading, then
(3) adjust corrected reading for wort temperature (http://www.brewersfriend.com/hydrometer-temp/); and
(4) plug adjusted numbers into the formula below to calculate ABV?

ABV = (OG-FG) / 7.46 + 0.5

This makes sense to me as it is correcting for dodginess and "normalising" for temperature, but it would be nice to confirm.

Thanks all.
6. After a couple more years of brewing which can develop procedures and processes (repetition & consistency); hydros, refracts, efficiencies, srms, alpha acids, abvs, etc. may become redundant. eg experience can educate
 

felten

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Is it one of the plastic coopers hydrometers, or a glass one?
 

Edak

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did you use distilled water at 20C? If not then you might be incorrect in your findings/corrections.
 

wbosher

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I had the same problem with the Coopers one, they told me to snip a little bit of the plastic off the top, that's what it's for. Just take off a few mm and test it again, if need be take a little more.

Some are faulty and take on water, but this is rare apparently. I ended up chucking mine and getting a glass one in the end.
 

cremmerson

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Thanks all.

The kit was a gift that wasn't used for more than two years, so the return is out of the question. And it is a plastic hydro. And yes I use distilled water at 20C.

Fine - may eventually make the change and buy a new one that works - but in the meantime will treat my hydro reading as a foreign expert: translate and get the joke second hand.

Thanks for the feedback and advice, all, very much appreciated.
 

cremmerson

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Thanks all.

The kit was a gift that wasn't used for more than two years, so the return is out of the question. And it is a plastic hydro. And yes I use distilled water at 20C.

Fine - may eventually make the change and buy a new one that works - but in the meantime will treat my hydro reading as a foreign expert: translate and get the joke second hand.

Thanks for the feedback and advice, all, very much appreciated.
 

cremmerson

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Thanks all.

The kit was a gift that wasn't used for more than two years, so the return is out of the question. And it is a plastic hydro. And yes I use distilled water at 20C.

Fine - may eventually make the change and buy a new one that works - but in the meantime will treat my hydro reading as a foreign expert: translate and get the joke second hand.

Thanks for the feedback and advice, all, very much appreciated.
 

Yob

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Despite their faults, as I understand it the customer service is said to be outstanding.. If it were me I would send them an email and see what comes of it..
 

wbosher

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You're right Yob, the customer service is excellent. Chances are you won't need to replace it, I just wanted a glass one.

I did email them about my one and I posted their response here.
 

Scottye

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Hey cremmerson
wbosher is correct. The way I understand it isn't dodginess but Coopers made them read this way deliberatley so that you can snip off some of the red tip to calibrate it. Be careful though you can't stick pieces back on. I cut 20mm (in 4-5mm steps) from mine and now it is spot on, it was always repeatable. BTW mine was out by 5 points.
 

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