Adjusting Hydrometer readings for temp.

During all grain brewing, do you take the pre-boil hydrometer reading immediately after the sparge when the water is still 180 degrees? How do you adjust for that high temperature to get anything near an accurate reading.

I'm sure this is a bit of a dumb question, it just left me confused.

Chill the sample down 1st

I use a refractometer for my preboil gravities, since it automatically adjusts for temperatures.

You can cool down a wort sample by putting ice around the sample container. Or you can take the gravity reading, take the wort temperature, then adjust the gravity reading to the temperature.

yep cool the sample down

Bytor1100 said:

take the wort temperature, then adjust the gravity reading to the temperature.

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Not a good practice to place a room temp thin glass hydro in 170º + liquid but yes you "can" do it.


Throw the sample in the freezer for about 10 min then adjust for temp when it gets 90º or lower.

Drunkensatyr said:

Throw the sample in the freezer for about 10 min then adjust for temp when it gets 90º or lower.

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This is what I do as well. For me anyway, the whole purpose of a preboil reading is to find out if I need to make adjustments before I start the boil.

I think that this is what you're looking for:

http://www.ebrew.com/primarynews/ct_hydrometer_temp_correction.htm

I chill a sauce pan in the freezer before I start the mash.
It has enough mass to cool a cup of wort down PDQ.

I would put it in the freezer when I had that issue. Now I use my refractometer.

I found though, that most of the time my numbers are insanely consistent and I don't need to worry about preboil gravity. I just take it now because the refractometer is fun.

I set it in the fridge in labeled cups along with 1st and 2nd running cups. while the BK is coming to boil I take the readings then dump them into the boil. my #'s are fairly consistent from batch to batch runnings also, I do it simply to check efficiency.

I haven't had good luck adjusting for temperature, so I started cooling my samples, but I quickly got tired of that so I bought a refractometer.. :rockin:

carnevoodoo said:

I would put it in the freezer when I had that issue. Now I use my refractometer.

I found though, that most of the time my numbers are insanely consistent and I don't need to worry about preboil gravity. I just take it now because the refractometer is fun.

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+1! I just bought my refractometer and LOVE my new toy. Sometimes I'll take readings during the boil just because I can.

When I first started brewing, I never took any pre-boil measurements. I wasn't concerned about my efficiency. I just wanted to brew beer. Granted I started brewing over 20 years ago too. Now with the internet, and forums like this one, I now understand why you would take this measurement.

ohiobrewtus said:

This is what I do as well. For me anyway, the whole purpose of a preboil reading is to find out if I need to make adjustments before I start the boil.

I think that this is what you're looking for:

http://www.ebrew.com/primarynews/ct_hydrometer_temp_correction.htm

Click to expand...

Same link I would have suggested.....used it yesterday for my first AG, and things went smashingly. Damn near perfect. Good luck to ya man!