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MRB Josh R

Hydrometers and Specific Gravity 101

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One of the first steps in checking FG is to sanitize the tube and hydrometer. If you fill the tube from the spigot, take your reading, then drink it, is it really necessary to sanitize the tube and hydrometer? It's obviously not going back into the LBK and I would assume if the equipment has been cleaned properly, it would not affect the reading of the FG

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Perhaps a dumb question but to take a sample from 2 gallons to see if the gravity is stable means taking at least two and possibly three fairly significant amounts of beer from a relatively small batch... I know that brewers have apoplexy at the idea of anyone returning a sample to the fermenter.. so my question: given the propensity for hydrometers to break and given their cost (about $7- 10 a pop) and given the fact that you should not return the sample to the hydrometer does it make any sense to buy a refractormer (initial cost about $30) since they require only a drop or two of the beer to measure the gravity (using the fact that sugar refracts light differently than pure water)? How easy is it to use a refractometer to measure the gravity of beer after the yeast has been pitched and there is now alcohol as well as sugar in the beer? (I believe that there are calculators on line that convert the Brix scale to FG) - and, does anyone know if the hops in the beer will distort the reading so that it becomes unusable to gauge the gravity to tell if the beer is ready for bottling? I have a birthday coming up and I was thinking of getting myself a gift of a refractometer if they can be used to measure the FG of my beer.  Thoughts?

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Refractometers are great tools, especially for winemakers (because you can see the brix of any fruit instantly). You can take a final gravity reading, but you have to factor in the alcohol so you'll need to use a refractometer adjustment calculator. But because refractometers are designed for sugar water and fruit juice, not wort, you'll also have to figure the Wort Refraction Index to get an accurate reading. I recommend reading this:

http://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/

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Moving this here instead of a previous discussion with JoshR because this thread is solid on topic and pinned.

To confirm: The current production plastic body Mr. Beer hydrometer for sale on the website is calibrated to 59°F (not 68°F), is that correct? I presume Mr. Beer does not manufacture this hydrometer themselves, they have sourced it from a third party and have either specified a 59°F calibrated hydrometer to the third party, or have been explicitly told by the third party that it is calibrated to 59°F, is that correct? (Many of the specific gravity temp correction calculators specify that "old" hydrometers are 59°F and "new" hydrometers are 68°F. I still have not received explicit confirmation that this is a newly manufactured hydrometer based on the "old" design.)

Also, the Mr. Beer hydrometer video lists the ABV calculation as:

"(OG-FG) x 131"

Why does RickBeer cite:

"(OG-FG) x 131.25"?

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Thanks for this video!

 

I knew I wanted a hydrometer to try to figure out my ABVs, so I just purchased one.

However, i had no idea how - or when - to use it (and if you should pour the beer back into the keg or drink it, etc.)

 

To my surprise, my hydrometer arrived today - with no instructions at all.

Unless I'm overlooking them: I didn't see instructions on the website, neither (where I purchased it)

 

But thankfully all of you already asked/answered the questions i was going to ask, and MRB Josh R gave the video, so i'm ready to go!

Great job, forum members!

 

Davz13

 

p.s. Well, 1 question: I didnt feel like waiting for this to arrive, so I started my brew a few days ago. Should I take a reading today - and at the 2 or 3 week mark - to get a guesstimated reading...or should i just wait to use it until my next batch?

(I can at least use it on this brew to see if it is ready to bottle!)

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9 minutes ago, Nightwulf1974 said:

While I know how to use a hydrometer after watching several videos and reading online, the video here is marked "private" and is unwatchable for me.  I'm logged in too.  Maybe it's just me, but I wanted to mention it if it isn't. 

 

It's not you. That video has gone away for some reason. I have removed it from the post. The video Rick posted still works, though.

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Just now, MRB Josh R said:

 

It's not you. That video has gone away for some reason. I have removed it from the post. The video Rick posted still works, though.

 

Ya, I already knew how to do it, but I digest as much as I can and watch many videos since I've started.  Thanks Josh.  Anything Rick posts is money. 

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Since we’re talking about taking a lbk sample I have a question.....after you whisk up the wort/water mix in the lbk do you just take a sanitized something to draw some wort out for OG before pitching? Or do you use the spigot?

 

before bottling after 3 weeks do you take a FG sample and then wait a few days and take another? Do you use the spigot and then resanitize it? Or just take a FG sample while bottling to determine abv and just roll with it? I definitley want a hydrometer. Next time mrb offers free shipping I will throw one in with my order. 

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