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Old 12-07-2012, 07:32 PM   #1
ADemon
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Default OG too low?!?! I'm out of explanations

Friends (drunk or sober),

I'm fairly new to all grain brewing, but I'm doing OK...I think I basically 'get it'.
Howeer, I've been struggling with low OGs on this IPA I'm trying to make. I've made it 3 times and I keep coming up .01 to .02 low on my OG! This sucks! I cant figure out why and I'm looking for help. Heres the scenario:
13.5lbs 2-row
1 lb cara-amber
3.5 Gallons mash water
mash for 60min at between 152 - 147deg
iodine test = good (no purple)
sparge (using a sprinkler head i connected to a kettle) with 175deg water.
collect maybe 6.2G wort (too much?) and boil for 60-70min
....Boil off a little over a gallon
Collect 5Gallons.
Test OG = 1.055....target OG = 1.065...So, I'm low by a lot! And this is the BEST I've done. one time it was more like 1.045.

Any thoughts?...problem in my sparging? Collection? I'm stumped!

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Old 12-07-2012, 08:36 PM   #2
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You seem to have the basics down and just need to tighten up your efficiency. I'd start with your crush and then look at your sparge technique. If your grains are properly crushed change up your sparge and see if you get better results. Until I got my fly sparge nailed down my eff. #s were all over the place. Go with batch sparge for starters and see if your #s improve.

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Old 12-07-2012, 08:38 PM   #3
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It looks like your grain to grist ratio is lower than I've ever done (1:0.9). I'm usually in the 1:1.25 range, but I can't say that it shouldn't give you good conversion. I would try to get at least a 1:1 ratio if it were me.

Another possibility is if you're having channeling occur using your sprikler sparge head, or some other technical difficulty. If you're not totally opposed to it why don't you try a batch sparge next time and see if it helps.

My two suggestions would be:
1) Up your water to grist ratio to about 1:1.15 (4.25 gallons mash water)
2) Batch sparge to achieve your pre-boil amounts

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Old 12-07-2012, 09:15 PM   #4
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I batch sparge. For 14.5 lbs of grain I would be mashing with 4.5 gallons of water (1.25 quarts of water per 1 lb of grains). I also make sure to stir very well when I add the grains. I stir for over 5 minutes and a couple more times during the mash, making sure my temperature is right where it needs to be. I vorlauf and drain the mash tun. I then sparge twice with equal amounts of water to get up to my preboil volume. I stir very well after adding water each time, let it rest, vorlauf, and drain. Doing this gets me right at or just above my expected OG with store milled grains. If you feel your grains are milled properly, maybe you can try this. Try a batch sparge, mash with more water, and stir until your arm hurts.

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Old 12-08-2012, 04:06 PM   #5
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This is really good advice....thank you very much!
Quick follow-up: When you "vorlauf" (that's the first I've heard this word, but I assume it means recirculating the wort), how much of the wort are you recirculating back into the mash? i.e. a gallon...2 gallons....all the wort?
And, when you recirculate ("vorlauf"), I assume you pour it carefully back into the mash so as not to disturb the grain bed? Or doesnt this concern you too much?

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Old 12-08-2012, 04:14 PM   #6
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You are vorlaufing until it runs clear (w/out grain debris), in my case that is usually 1-2 quarts.
Sure, pour it carefully back in mash, you can use some kid of lid for this, just to prevent disturbing grain bed.

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Old 12-08-2012, 04:39 PM   #7
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I vorlauf 2 quarts out of habit, but that's right, the wort should be somewhat clear. It won't be crystal clear, but you'll see it clearing up as it's flowing out of the hose. I'm not sure how necessary it is, but I do it out of habit and it takes little effort. I vorlauf into a 2qt pitcher and as the wort is reaching the top I transfer the end of the hose to the brew pot and slowly pour the collected wort from the pitcher back over the grains. I do the same with each sparge.

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Old 12-09-2012, 12:15 AM   #8
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Dumb Question: how are you checking gravity? if you're using a hydrometer, are you adjusting the observed measurement for temperature? a hydrometer will not read accurately unless the liquid you're measuring is about 68 deg F. you have to apply an offset multiplier for higher or lower temperatures.

if you're measuring using a refractometer, I always stir the wort before measuring, because I've seen stratified measurements in finished wort before stirring.

Outside of this, the majority of low OG problems seem to be able to be tracked back to grain crushing. if your LHBS is grinding, maybe just once you might consider buying a grain bill from someone else and see if you have the same prob. or if you're grinding, have the LHBS do it.

your water for mash seems low to me. I would have done about 5 gals for that grain bill myself.

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Old 12-09-2012, 01:23 AM   #9
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If you are getting low OG, then you either have a problem with measurements, or you are getting low efficiency (or both).
Let's look at some of the more common measuring problems to start with:

  • Are you measuring OG with a refractometer? If so, have you cross checked the results with a calibrated hydrometer?
  • If you are measuring OG with a hydrometer:
    • Have you checked the accuracy of the hydrometer be measuring the density of water at the calibration temperature?
    • Do you take the sample at close to the calibration temperature (within 20F) and applied temperature correction if it is different than the calibration temperature?
  • Do you always mix the wort thoroughly before taking the sample for checking? This is very important for a pre-boil sample, or after topping off with water.
  • How do you judge volumes? Be aware that volumes at boiling point are about 4% higher than those at fermentation temperatures. Also be aware that the volume markings on ale pails are ofter very inaccurate.
If your measurements are good, then you need to check your efficiency. http://braukaiser.com/wiki/index.php...ing_Efficiency gives some excellent advice in diagnosing the cause of efficiency problems.


From your OP, it looks as though you are fly sparging. This can work well with the right equipment, and if you take long enough to sparge; but can be a disaster if you use a braid or improperly designed manifold to collect the wort or if you sparge too quickly. I fly sparge with a cylindrical cooler and a false bottom. With a grain bill like yours, it would take me about 90 minutes to sparge.


Batch sparging may lose a few percentage points in efficiency vs a set-up optimized for fly sparging, but is much faster, and not so equipment and procedure related.


I found when I started doing a mash out before fly sparging (adding 5 - 6 qt boiling water, and stirring really well), my mash/lauter efficiency increased from 75% to 85%


The last thing is equipment losses. I typically get 85% mash/lauter efficiency, but only about 75% brewhouse efficiency. The reason is I lose wort to hop absorption, trub, dead space in equipment, wort trapped in the CFC etc.


Whatever, the first step is to determine where you are losing efficiency. Once you know that, you can take steps to address the problem, but if you don't know what the problem is, it is unlikely that you will be able to fix it.


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