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Hydrometre Readings - Which One ?

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Desert Brewer

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Just taken a reading as i am about to crash chill the brew for a week or so.

The reading is 1010 - about 1 - 2 mins out of the fermenter. I was mucking around in the garden and left the hydrometre upright in the vice and came back about 20 - 30 mins later and its reading 1006 or there abouts.

I have always taken the reading that i get 1- 2 mins out of the fermenter, which is generally at ferment temp of 18 degrees + or - a couple, unless i am brewing a lager.

Is there any reason why the SG lowers after 20 - 30 mins? Its pretty hot in the shed at the moment - as the wort gets up to a temp in the hydrometre - is there a mini ferment going on lowering the SG ?

Im sure there is a simple explanation - i just cant think of it at the moment :huh: !

Cheers,

DB
 

warra48

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Just taken a reading as i am about to crash chill the brew for a week or so.

The reading is 1010 - about 1 - 2 mins out of the fermenter. I was mucking around in the garden and left the hydrometre upright in the vice and came back about 20 - 30 mins later and its reading 1006 or there abouts.

I have always taken the reading that i get 1- 2 mins out of the fermenter, which is generally at ferment temp of 18 degrees + or - a couple, unless i am brewing a lager.

Is there any reason why the SG lowers after 20 - 30 mins? Its pretty hot in the shed at the moment - as the wort gets up to a temp in the hydrometre - is there a mini ferment going on lowering the SG ?

Im sure there is a simple explanation - i just cant think of it at the moment :huh: !

Cheers,

DB
Probably two simple things:
1. CO2 bubbles clinging to your hydrometer. Spin the hydrometer to dislodge those.
2. The sample warming up. As a brew warms, the reading lowers, hence the need to adjust readings for temperature.
 

mondestrunken

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Possibly CO2 bubbles attaching to the hydrometer and making it more buoyant?

I normally give the hydrometer a spin before reading to dislodge any bubbles.
 

Desert Brewer

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Damn it warra48 beat me by one minute!
Thanks Mondestrunken and Warra - i always give it a good spin to dislodge the bubbles.

What is the ideal temp to take a reading? - as everyones room temp is different - the temp in my shed today is about 43 degrees.
 

NewtownClown

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Thanks Mondestrunken and Warra - i always give it a good spin to dislodge the bubbles.

What is the ideal temp to take a reading? - as everyones room temp is different - the temp in my shed today is about 43 degrees.
Depends on the hydro. some are calibrated at 15C, others at 20C. most in Oz are 20 but you should check, it may be printed on the hydro.
If not float it in water at 20C and if it read 1.000 then it is calibrated for 20 and use that in one of the many online hydro adjustment calcs on the web or in Beersmith tools
 

manticle

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Just taken a reading as i am about to crash chill the brew for a week or so.

The reading is 1010 - about 1 - 2 mins out of the fermenter. I was mucking around in the garden and left the hydrometre upright in the vice and came back about 20 - 30 mins later and its reading 1006 or there abouts.

I have always taken the reading that i get 1- 2 mins out of the fermenter, which is generally at ferment temp of 18 degrees + or - a couple, unless i am brewing a lager.

Is there any reason why the SG lowers after 20 - 30 mins? Its pretty hot in the shed at the moment - as the wort gets up to a temp in the hydrometre - is there a mini ferment going on lowering the SG ?

Im sure there is a simple explanation - i just cant think of it at the moment :huh: !

Cheers,

DB
Temperature affects gravity reading - the higher the temperature, the lower the reading so it's most likely just that the wort has heated up if the conditions in Alice are like I remember them to be this time of year.

Calibrate your hydrometer in 15 or 20 degree water (the actual difference there is pretty minimal) and try and do your readings around the same temp.
 

Desert Brewer

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Temperature affects gravity reading - the higher the temperature, the lower the reading so it's most likely just that the wort has heated up if the conditions in Alice are like I remember them to be this time of year.

Calibrate your hydrometer in 15 or 20 degree water (the actual difference there is pretty minimal) and try and do your readings around the same temp.

Thanks for input - i reackon your memory is right Manticle, its pretty warm here, although a bit cooler than it has been over the last couple of weeks. I will take it that the reading at about 1- 2 mins out of the fermenter at approx 18 degrees is the correct one and in which case thats 2 days at 1010 and into the cube it goes for a week or 2 at 2 degrees.


Thanks again,

DB
 

Desert Brewer

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Temperature affects gravity reading - the higher the temperature, the lower the reading so it's most likely just that the wort has heated up if the conditions in Alice are like I remember them to be this time of year.

Calibrate your hydrometer in 15 or 20 degree water (the actual difference there is pretty minimal) and try and do your readings around the same temp.

Thanks for input - i reackon your memory is right Manticle, its pretty warm here, although a bit cooler than it has been over the last couple of weeks. I will take it that the reading at about 1- 2 mins out of the fermenter at approx 18 degrees is the correct one and in which case thats 2 days at 1010 and into the cube it goes for a week or 2 at 2 degrees.


Thanks again,

DB
 

Desert Brewer

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Thanks for input - i reackon your memory is right Manticle, its pretty warm here, although a bit cooler than it has been over the last couple of weeks. I will take it that the reading at about 1- 2 mins out of the fermenter at approx 18 degrees is the correct one and in which case thats 2 days at 1010 and into the cube it goes for a week or 2 at 2 degrees.


Thanks again,

DB

Two replys are better than one :rolleyes: - it is hot here after all.
 

mondestrunken

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John Palmer's Hydrometer temperature correction table has a 0.007 difference between 20 and 43 degrees, which seems pretty close to the numbers you're describing.

Basically, the liquid is expanding as it heats up and so becomes less dense (and so lower SG reading).

Cheers.
 

thylacine

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Ahhh! I enjoy this brewing stage where REPETITIVE 'house brew recipes/processes' have established themselves. eg. grist totals, mash temps, etc. As a result, no OG, SG and maybe a FG. Set the temp controller and leave everything alone. With a single view per day to see the krausen status. Too easy... RDWHAHB ;-)
 

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