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My gravity is off what the software says, what does this mean?

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snarf7

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OK, so first few batches I didn't pay attention to any of this ****, just threw some ingredients together in the right order and it worked out pretty well. But then I started reading all about gravity and how to measure it and I bought a hydrometer and I'm trying it for the first time.

So in Brewtarget, I enter all my ingredients and it calculates the OG for me to be 1.065. When I measure it however (just before pitching yeast), I got a reading of 1.072. What does this mean? What does it tell me about how I did my boil? Is this within the normal standard deviation or did I maybe mess something up?

cheers!
 

Konadog

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What was the batch size (gallons) "vs" what you ended up with? If it's less than the batch size then that would account for some, if not all of it.
 
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snarf7

snarf7

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What was the batch size (gallons) "vs" what you ended up with? If it's less than the batch size then that would account for some, if not all of it.
Just a small 1 gallon batch...Usually I wind up less volume than I need so I top it off with water before adding the yeast. Does that have an effect on these numbers or is it only the fermentables that factor in?
 

Jtk78

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Could be a couple different factors. The one you'll hear the most is you didn't stir the wort and the top up water enough and had a concentrated sample. Another possible cause is you're volume was still slightly less than you gallon.

This is a little tricky to understand, but once you get the concept, you can use it to confirm hydrometer readings of any batch.

Instead of 1.065 I'm going to say this is 65 gravity points.
65 x 1(gallons) = 65 total gravity points

65 total gravity points ÷ .9 gallons = 72 So if you had .9 gallons of beer instead of 1, you will in fact have an OG of 1.072

Another example (5 gallon batch)
6 (pre-boil volume) x 50 (pre-boil gravity of 1.050) = 300

300 ÷ 5 (post boil gravity) = 60

So this should have an after boil gravity of 1.060.

What does it mean?? It means you made beer. Perhaps one a little stronger than intended. Nothing to worry about in the least. Also means it's time to plan the next one!
 
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snarf7

snarf7

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Could be a couple different factors. The one you'll hear the most is you didn't stir the wort and the top up water enough and had a concentrated sample. Another possible cause is you're volume was still slightly less than you gallon.

This is a little tricky to understand, but once you get the concept, you can use it to confirm hydrometer readings of any batch.

Instead of 1.065 I'm going to say this is 65 gravity points.
65 x 1(gallons) = 65 total gravity points

65 total gravity points ÷ .9 gallons = 72 So if you had .9 gallons of beer instead of 1, you will in fact have an OG of 1.072

Another example (5 gallon batch)
6 (pre-boil volume) x 50 (pre-boil gravity of 1.050) = 300

300 ÷ 5 (post boil gravity) = 60

So this should have an after boil gravity of 1.060.

What does it mean?? It means you made beer. Perhaps one a little stronger than intended. Nothing to worry about in the least. Also means it's time to plan the next one!

Oh duh, that explains it then. Because my wort had boiled down to be more concentrated than the final desired 1 gallon. And to take my measurement I scooped out enough to put in the hydrometer BEFORE I added the additional water to get back to 1 gallon. That's what threw it off.

OK 2 follow up questions

1)I assume this completely hoses my calculations for the FG too right? Like after fermentation I'll get the actual correct FG reading but since I didn't do the OG correctly I can't calculate ABV properly other than to guesstimate it really?

2)The boil pot I used is 12 qt (4 gal) so you can kinda estimate how much is in there after a boil but it's not exact. And I am fermenting in a carboy so how do you typically do this to get an exact reading? I could transfer to the carboy, top it up with water and then try to float the hydrometer but I don't want to lose that little bugger, not sure if that would work. I guess I need a 1 gallon pail to ferment in that would make this easier?
 

RM-MN

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When brewing with extract, if you get the amount of water right you got the correct OG whether it measures right or not. It is difficult to get the wort mixed well enough when you add top-off water so just take the kit's estimate as the correct OG. The final gravity (FG) is partially determined by the extract's makeup and partly by the yeast so it can vary from batch to batch. To get the ABV, take the kit's estimated OG and your measured FG to calculate.
 

BrewnWKopperKat

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2)The boil pot I used is 12 qt (4 gal) so you can kinda estimate how much is in there after a boil but it's not exact. And I am fermenting in a carboy so how do you typically do this to get an exact reading? I could transfer to the carboy, top it up with water and then try to float the hydrometer but I don't want to lose that little bugger, not sure if that would work. I guess I need a 1 gallon pail to ferment in that would make this easier?
A two gallon food grade pail for fermentation will definitely make wort volumes easier to work with. The "problem" with one gallon carboys (at least the ones that I have) is that it's hard to ferment 128 oz of wort in them. To avoid 'blow offs', one often fills the carboy mostly full (around 120 oz?).

Pay attention to the amount of hops that you use. An oz of hops in a one gallon hoppy ale will leave a measurable amount of trub in the fermenter if one just pours all the wort from the kettle into the fermenter.

For measuring OG in small batches, a refractometer is an option to consider. Note that refractometers can't measure FG directly, but the "brix" measurement can be converted to FG using software.

Floating a hydrometer in 5 gallon fermenters works. With a one gallon carboy (or two gallon food grade pail), I'm not aware of a hydrometer that is short enough to float. One can test this quickly with the container, the hydrometer, and a gallon of water.
 

Jtk78

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Oh duh, that explains it then. Because my wort had boiled down to be more concentrated than the final desired 1 gallon. And to take my measurement I scooped out enough to put in the hydrometer BEFORE I added the additional water to get back to 1 gallon. That's what threw it off.

OK 2 follow up questions

1)I assume this completely hoses my calculations for the FG too right? Like after fermentation I'll get the actual correct FG reading but since I didn't do the OG correctly I can't calculate ABV properly other than to guesstimate it really?
FG is final gravity and is not volume dependant. For this batch I would use the 1.065 as your SG for ABV calcs.

2)The boil pot I used is 12 qt (4 gal) so you can kinda estimate how much is in there after a boil but it's not exact. And I am fermenting in a carboy so how do you typically do this to get an exact reading? I could transfer to the carboy, top it up with water and then try to float the hydrometer but I don't want to lose that little bugger, not sure if that would work. I guess I need a 1 gallon pail to ferment in that would make this easier?
Depending on what you are using for a spoon you could mark the volumes on that by 1/4 gallon. Put a quart on the pot, hold spoon in verticle position and notch / cut spoon and continue going up to desired levels. I know people that have used a punch and dented pots at certain levels (honestly didn't work great). I did a trick I found using vinegar, a 9v battery and a wire to mark volume markings on the inside of 2 pots. It worked great and has lasted well over a year. Refractometers do work well for small batches. There are online calculators for use after fermentation, but I do not know how accurate they are. I have never floated a hydrometer in a carboy, but have heard of them breaking in them before, ruining a batch.
Answers above on red.

Cheers!
 

RM-MN

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A two gallon food grade pail for fermentation will definitely make wort volumes easier to work with. The "problem" with one gallon carboys (at least the ones that I have) is that it's hard to ferment 128 oz of wort in them. To avoid 'blow offs', one often fills the carboy mostly full (around 120 oz?).

Pay attention to the amount of hops that you use. An oz of hops in a one gallon hoppy ale will leave a measurable amount of trub in the fermenter if one just pours all the wort from the kettle into the fermenter.

For measuring OG in small batches, a refractometer is an option to consider. Note that refractometers can't measure FG directly, but the "brix" measurement can be converted to FG using software.

Floating a hydrometer in 5 gallon fermenters works. With a one gallon carboy (or two gallon food grade pail), I'm not aware of a hydrometer that is short enough to float. One can test this quickly with the container, the hydrometer, and a gallon of water.
Good point and I'd suggest that the calculated FG taken from any refractometer reading are estimates. Much better to use the hydrometer then. With that in mind, drinking the hydrometer sample for OG is tough because to me it just tastes bad but the final gravity sample will tell you quite a bit about the beer itself so I us the refractometer for OG and hydrometer for FG.
 
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