do other solids effect OG reading

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scottfro

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Do hop particles and other solids floating around in your hydrometer tube after the boil effect the OG reading? It seems that they could contribute to displacement of the hydrometer and offset the reading or is this not an issue in any way?
 

iamjonsharp

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1. EPA website
"Adding more suspended solids to a liquid may increase or decrease the density of the liquid. If the density of the suspended solids is less than the density of the liquid, then the volume of the liquid will increase more than the mass and the density of the mixture will decrease. If the density of the suspended solids is greater than the density of the liquid, then more mass is being added than volume and the density of the mixture will increase."
http://www.epa.gov/eogapti1/module4/gravity/txt_answer/t_answer.htm#2tt

2. Mr Wine Wizard says the opposite:
"It’s easy to see that if you’ve got lots of little bits of suspended pulp helping the hydrometer to float well above what would be its natural level you’re going to get an artificially high reading."
http://winemakermag.com/mrwizard/160.html

3. Mr Beer Wizard says no effect:
"Although suspended solids, such as trub and hop particles, should not affect the hydrometer reading — since hydrometers measure dissolved solids — I collect a sample and first allow the solids to settle, then transfer clear wort to my hydrometer test container."
http://byo.com/mrwizard/1002.html

Take yer pick. I'd go with #1. I'm not sure how much of an effect there will be. Try a reading before the trub settles, then try it again w/o the trub and strain out the hop particles.
 

Orfy

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You are not weighing the liquid or measuring the volume.

So if the particles are not impeding the free floating of the hydrometer, it will NOT change the density.

Only the type of liquid or dissolved additives will change the density.

# 3 make sense to save any errors.
 

Sea

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I agree, let your sample sit until the non-sugar solids settle out (doesn't take long), too be sure you get an accurate reading. There's no real rush.
 

iamjonsharp

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orfy said:
You are not weighing the liquid or measuring the volume.

So if the particles are not impeding the free floating of the hydrometer, it will NOT change the density.

Only the type of liquid or dissolved additives will change the density.

# 3 make sense to save any errors.
I'm not 100% sure about this. I remember using hydrometers in the soils lab to measure soil grain size. Fine soil was mixed in water (or some other solution) and we would measure the change in hydrometer readings over time as the soil particles settled out.
 
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scottfro

scottfro

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iamjonsharp said:
I'm not 100% sure about this. I remember using hydrometers in the soils lab to measure soil grain size. Fine soil was mixed in water (or some other solution) and we would measure the change in hydrometer readings over time as the soil particles settled out.

heheh i did the same, thats why i asked the question. i think letting it settle for a bit is the easiest solution. might be interesting to do it over time as well to see how much the particles really do effect it.
 

pjj2ba

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+1 on #3. Just let it settle.

Also, dissolved CO2 will affect hydrometer reading. Typically by the time a beer is ready to bottle or keg, there will be more CO2 dissolved in the beer compared to a sample prior to fermentation. This will affect the SG, making it appear higher. I always give my hydrometers a good spin and if I see a fair number of bubbles, I wait a little longer and I keep doing this until I see few bubbles, then I record my FG.
 

david_42

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Since the particles in question are near the same density as the wort, I think the difference will be less that what you can read. Leaving the hydrometer in the tube while the particles settle can result in a pile on top of the hydrometer. Which has on occasion, produced a small but noticeable error.
 
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