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-   -   OG WAY too low on extract batch (http://www.homebrewtalk.com/f39/og-way-too-low-extract-batch-386864/)

thefugal 02-03-2013 12:39 AM

OG WAY too low on extract batch
Hi everybody,

I just finished my brew day. Made a Belgian Strong Golden Ale extract batch. My problem is, I undershot the OG by a HUGE margin. As in, iBrewMaster expected an OG of 1.073, and I ended up with 1.045. What confuses me is the fact that this was an extract batch -- I could understand coming in low on an AG batch if you don't have a high enough efficiency, but I pretty much just poured sugar into water.

I only have three thoughts:

1) This is my first time using Whirlfloc, and I had a HUGE amount of sediment in the kettle. I left about 1 cm on the bottom of the brew kettle. I am sure I lost sugar in that cm of wort. But I didn't expect it to be that drastic of a drop.

2) I was on autopilot after transferring from the kettle to the primary, and I started filling my hydrometer test jar before I topped off my partial boil volume (I can only boil about 2.5 gallons in my kettle) to the full 5 gallons. Obviously that hydrometer reading would be wrong, and I didn't want to risk contamination, so I threw out about 1/2 test jar of concentrated wort. Again, I know I lost sugar there, but I wouldn't expect that drastic of a drop.

3) As I said, it was my first time using Whirlfloc. I followed instructions I found on the forums for using it -- I added 1/2 of a tablet to the last 15 minutes of my boil. Is that the right thing to do, even considering I'm doing a partial boil at about 2.5 gallons?

Really curious where all my fermentables went. I was hoping to make a Strong Golden Ale in the 7-9% range, but I think I'll probably end up with a Weak Golden Ale in the 3-4% range. Still beer, but not what I was hoping for. I want to figure out what I did wrong so that I can fix it for the next batch. Thanks in advance for any help!

In case it's helpful, here's the recipe I used:

- 4 oz Carapils (steeped 155 for 30 min)
- 4 oz Biscuit malt (steeped 155 for 30 min)
- 7 lbs light DME (added half to the boil immediately, reserved half to the end of the boil ~10 min)
- 2 lbs light candi sugar (added at the end of the boil ~10 min)
- 1/2 tablet Whirlfloc (15 min)
- 2 oz Saaz (60 min)
- 1 oz Saaz (1 min)

Yooper 02-03-2013 12:53 AM

If you used 7 pounds of DME, and 2 pounds of candi sugar in a 5 gallon batch, then your OG has to be 1.076. It has to be- the sugars can't go anywhere.

Your reading could be less due to an inadequate mixing of top off water and wort, as the heavier wort sinks to the bottom and it's very difficult to mix well and get a good reading.

thefugal 02-03-2013 05:36 AM

That makes a lot of sense. I feel much better now. Thank you!

Qhrumphf 02-03-2013 05:45 AM

It's a very common issue posted on here. Wort is much denser than water, and the two don't mix well at all. Even with a tremendous amount of stirring or shaking, you can't guarantee an accurate reading. But like Yooper said, the sugar content of extract doesn't change, so the only way to miss your gravity reading is A) you didn't add the proper amount of fermentables, B) your volume wasn't correct, or C) the maker of the kit/recipe messed up.

There's a very simple trick I use (while I brew AG for the most part, I'm still limited to partial boils). If you can accurately measure your volume after the boil, but before you top off, take your gravity reading then. Your gravity (expressed as "gravity points" ie 1.076 would be 76) x your volume = your gravity at a different volume x that volume. So 2.5 gallons of chilled wort post boil reading 1.100 if topped off to 5 gallons would be 100(2.5)= gravity x (5) = 50, or 1.050. Never have to second guess your gravity readings again.

thefugal 02-03-2013 07:57 AM

Clever. I'll have to give that a try next time. Thanks for the tip!

Qhrumphf 02-03-2013 02:22 PM


Originally Posted by thefugal (Post 4859055)
Clever. I'll have to give that a try next time. Thanks for the tip!

It's the same math used for preboil gravity readings, and since the sugar content of wort remains the same while boiling off water, the same holds true for adding water back. Just important you can accurately measure the volume. Or you calculations will be off.

eric19312 02-03-2013 02:26 PM

This happened to me once. And then I found my second addition of LME sitting on the counter....

thefugal 02-03-2013 06:13 PM

Ha! I triple-checked the garbage can. I am certain that I actually put in all the extract.

saxman1036 02-03-2013 06:37 PM

I had a similar problem yesterday with a 5.5 gal Imperial Stout all-grain batch of mine. Here was the recipe...
18 lbs Pale Ale
.6 lbs Roasted Barley
.6 lbs Choc Malt
.6 lbs Med Crystal
.6 lbs Black Malt
I mashed the whole deal in a 10gal cooler.

This is only my second all-grain brew, so I expected that with that many grains in a 5.5 gal batch I was planning on only about 60% efficiency. If I hit that, I expected to land in the mid-80's with my gravity readings. I was a little lower than that even, and I came in at 56%, and after stirring the wort, I measured 1.062 for 6.8 gallons of wort... so 1.077 equivalent for the 5.5 gallons I wanted.

I was bummed, but I sucked it up and figured "I'm just gonna boost this sucker up a little." After some research on the forums here, I added 1.5 lbs of extra light DME and 1/2C of molasses (~6.2oz), both within the last 15 minutes of the boil. These *should* have added ~16 points to my gravity. After chilling & moving to a carboy, I hit *exactly* the volume I wanted (fist-pump!), meaning I didn't need to top off with any water. Needless to say I was shocked when my gravity reading was only 1.083, as opposed to the 1.093 I was expecting. I was pissed, so I shook the &*%$ out of that carboy for a couple minutes. There was foam all the way to the top of the bung hole. And the new reading... you guessed it... 1.083.

Where the %$#@ is all my sugar going?? The ONLY thing I can think of is that the gravity of the wort is so crazy dense & heavy that I can't possible mix shake the carboy enough to get an accurate & representative sample of its gravity.

Alright, now that I've calmed down, a couple more notes on my issues...
1. I've had this problem with other beers recently. I generally brew big beers (at least 1.075), and the higher target gravity ones are further off from the target than the lower ones.
2. I did branch-out recently and brewed a lager. The expected OG was 1.047, and I came in at 1.048. I was super happy/confused.
3. I have purchased and tested a new hydrometer, it works fine.
4. I am considering buying a mix stir.

Is it possible that even after vigorously splashing and shaking the carboy that many of the sugars are still sitting on the bottom of the carboy and that I can't reach them with my siphon?

Squirrels 02-03-2013 06:53 PM

I guess one other thing that hasn't been mentioned is to check what temperature the wort was at when you took your reading. It could be off due to a higher temp reading.

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