missed my gravity, gravity fluctuating between batches...wtf

brewed today with anticipation of a 1.067 beer, came with 1.058. im really failing to make the connection of why i didnt hit my gravity. its actually been like every other batch i either do/dont hit numbers. last batch numbers were spot on, batch before too low, before that spot on, and so on. process remains the same and i use beersmith for calculation at what i thought was a 70% efficiency. without breaking down my brewday to every aspect (which i know must probably be done to get a legit answer) are there some standard factors why im getting low numbers every other batch?

Time to do some diagnostics.

Next brew day, follow the instructions here and document every step. This way, you'll be able to figure out where you are losing sugars.

Inconsistant grain crush at your LHBS perhaps?

@Malfet, thanks for that. i will read over that article thoroughly before my next brewday. i really have followed the same exact steps for the last several batches, which is why im kinda pissed when its been a hit and miss with my OG.

@GryphonBrew. i do get my grains from an online supplier pre-crushed. very well known supplier so i dont wanna name drop and hate if it isnt there fault. but you have made me decide to try out another online HBS to see if its possible...

Could just be a skewed beer sample for hydrometer reading. The wort sometimes settles into layers before fermentation agitates it all up. If you are pulling the sample off the top of the carboy, it could appear lighter in density (which is why it is on top).

I use the outer plastic tube from an autosiphon to pull a sample. It is long enough that I can get liquid from the whole height instead just the top section.

BadWolfBrewing said:

Could just be a skewed beer sample for hydrometer reading. The wort sometimes settles into layers before fermentation agitates it all up. If you are pulling the sample off the top of the carboy, it could appear lighter in density (which is why it is on top).

I use the outer plastic tube from an autosiphon to pull a sample. It is long enough that I can get liquid from the whole height instead just the top section.

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Interesting. Ive never heard (or thought) of that. Have you actually seen significant difference in readings with this method?

You're in the beginners section, are you brewing all grain or extract?

Revvy said:

You're in the beginners section, are you brewing all grain or extract?

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AG...for a while now. I guess I should post in the other section..

What about the actual weight of the grains?

I know you are using a reputable vendor and I cannot imagine any business shorting someone on purpose but we are human. I am at my LHBS when they weigh and crush my grains and they have "goofed" a few times, nothing major but still it can happen!

Just a thought

Yeah, being specific helps. The reasons are different often for ag over extract and pm. BadWolfBrewing was more than likely talking about what happens whenver top off water is involved. Water and wort don't mix up that well initially, so it skewes hydro readings- get more wort than water, higher grave than recipe calls for, get more water than wort, lower grav.

In your case, I think using malfet's link is a good thing. It could be anything in your case, inconsistant grain crush is my first thought.

Well, I did a search and found a post from a few days ago with someone who has the exact same problem. The person is using the same online HBS and suffered a low OG as well. Im convinced it must be the grain crush and contacted the HBS to see if I can get some kind of resolution. Although Im not sure exactly what they really can do...

zodiak3000 said:

Well, I did a search and found a post from a few days ago with someone who has the exact same problem. The person is using the same online HBS and suffered a low OG as well. Im convinced it must be the grain crush and contacted the HBS to see if I can get some kind of resolution. Although Im not sure exactly what they really can do...

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The easiest answer would be to get your own mill, that way you can control the crush all the time. Most folks just dial it in and leave it the same for each batch.

Revvy said:

Yeah, being specific helps. The reasons are different often for ag over extract and pm. BadWolfBrewing was more than likely talking about what happens whenver top off water is involved. Water and wort don't mix up that well initially, so it skewes hydro readings- get more wort than water, higher grave than recipe calls for, get more water than wort, lower grav.
. . .

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I think I've even had this happen in all-grain. I took a pre-boil measurement that was lower than I expected, extended the boil to make up for it, then ended up overshooting my OG. Now I make sure the wort is stirred really well after sparging before I take my pre-boil reading.

Yeah, I just assumed extract with a partial boil, sorry. Not applicable to AG. With AG, there are a lot more factors involved. With pre-boil measurements, I could see how the sparged wort isn't as dense possibly.

BadWolfBrewing said:

Yeah, I just assumed extract with a partial boil, sorry. Not applicable to AG. With AG, there are a lot more factors involved. With pre-boil measurements, I could see how the sparged wort isn't as dense possibly.

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Honestly we get this at least twice a day from extract brewers, so you were like me, right in assuming that he was talking extract, especially considering it is in the beginner's section.

Someone did recently mention this issue among preboil gravity readings, thinking that multiple runnings have different densities, I think it could be possible to have skewed pre-boiled gravity readings, but once it's boiling it's probably mixing fine.

When I brew ag I usually mash and sparge to a bucket with graduated measurements. When I hit my preboil volume I dump it into my kettle. I've never had a skewed reading that I could attribute to that phenomena when I brew since I'm sure the dumping of the combined runnings probably mixes it fine.

Really, could be an endless list of things:

- Are you keeping you water to grist (strike and sparge water) the same batch to batch?
- Higher gravity beers tend to experience a drop in efficiency.
- Perhaps the lower efficiency batches could have had PH issues due to large amounts of roasted grains when using water with low buffering capacity.
- Did you run off all of the beers at the same rate?