Hydrometer readings too low?

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saxman1036

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I've been finding that my hydrometer readings are consistently reading about 10 points too low. I know that having the wort too warm will bring the temp down a little, but there's no way that it's that warm. Also, when I measure final gravity, the readings also seem to be about 10 points too low. I've already replaced the hydrometer once, thinking that it was faulty, but the new one is giving me the same readings. Also, the apparent attenuation always appears to be the same, so I'm not really worried, just weirded out.

It's possible that I just have bad luck with hydrometers, but I get the feeling that I am doing something else wrong. Any ideas on what could be causing these numbers to be so far consistently off?
 

ChuckO

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If you want to get things very accurate, use a two point calibration. At least it will tell you how accurate the hydrometer is at both ends of the scale. See http://www.honeycreek.us/hydrocal.php for one method of calibration. I have found some hydrometers that don't have the curl of paper printed correctly.
 

pdxal

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Both hydrometers are giving you the same readings? Maybe your process is off and you are ending up with genuinely low OGs and FGs. I'd like to see what distilled water reads with both too.
 

Supergrump

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I am having the same issues. I've just stopped using it altogether because I consistently get low readings as well (around 10 points). It's been consistently low with extract batches as well as all-grain so I hope its not because of very poor efficiency. It's a bummer because I just built a new 5 gal cooler mash tun with a copper manifold and I was really eager to measure my efficiency.
Not sure what to do about it. Maybe invest in a refractometer?
 

duboman

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You needs to calibrate using distillers water at 60F.

Also, none of you mentioned the temp you are sampling at, anything over 100F is worthless as the corrections are very unreliable. You really want to sample as close to 60 as you can

A refractometer is good until the yeast is pitched, once alcohol is present you need to calculate brix and adjust

I've never had the issues your stating with hydrometers, they are usually very reliable
 

chuckstout

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I thought I was having this problem for a couple of brews, It was actually my grain crush as I run a stone grinder and the stones wore down or back off because i had never changed my oringial setting of about 70%eff, corrected the setting and back to 70%
 

ChuckO

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I am having the same issues. I've just stopped using it altogether because I consistently get low readings as well (around 10 points). It's been consistently low with extract batches as well as all-grain so I hope its not because of very poor efficiency. It's a bummer because I just built a new 5 gal cooler mash tun with a copper manifold and I was really eager to measure my efficiency.
Not sure what to do about it. Maybe invest in a refractometer?
Unfortunately, if you aren't using a calibrated hydrometer or a calibrated refractometer you will never know if it is poor efficiency or not. If you calibrate a hydrometer, at least at 1.000 with water, if not at two points, you will be able to say with certanty what the SG is. Then you can look for causes of a low reading. A refractometer should also be calibrated with water in order to use it properly.
 

amandabab

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check your water at the temp its calibrated for AND check it against a second different brand hydrometer.
check it at pitching temps and convert. do this with another brand too and cross reference
a $ 4.99 triple scale is not a precision instrument. Some are spot on, some aren't.
 
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saxman1036

saxman1036

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Thanks for the responses everyone.

I will check distilled water for some reference.

I usually do extract only, so I don't think that efficiency is the issue.

I suppose it's possible that the wort is still too warm. That wouldn't explain why the FG was off by as much though...
 

Supergrump

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+1 for 'too warm'. I measured my pre-boil gravity on the weekend and was discouraged again, then found this online:
http://www.brewersfriend.com/hydrometer-temp/
and others like it. Turns out that near-boil temperatures have a significant affect on gravity readings, which I didn't know.
I achieved the Brewsmith-recommended OG almost exactly as per my not-so-faulty hydrometer at room temp.
 

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