Low OG Issue - How to correct

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GeologyROCKS

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Hey All - forgive me if this isn't the best place to post my issue but I'm hoping the great brewing minds out there can help me out.

I attempted doing a partial mash BIAB and partial volume boil with the make up of gravity coming from DME additions. I suspect that my BIAB mash and sparge went very poorly resulting in a lack of fermentable sugars (mash temps were okay so I think my sparge failed me). My OG is about 1.025 instead of 1.063 as expected after putting in my make-up water to bring me to batch size.

Unfortunately my LHBS is closed tomorrow and I don't have any DME left on hand so I'm scrambling to figure out a fix. My thought is to pitch my yeast anyway hoping they protect the beer from oxidation though a little fermentation until I can add a DME slurry but I'm also worried about oxidation and stressing the yeasties out dumping a bunch of food in all at once. I recognise that this issue is best dealt with much earlier in the process but here we are.

Is that a reasonable idea or is this batch already toast? Wort has been cool for a couple of hours already if that makes a difference (thanks to an interrupted brew day by a surprise furnace issue).

Thanks in advance!
 
Dissolve the DME, boil it for a few minutes to disinfect and deoxygenate, cool and add. You should be fine. Curious, why do you think your gravity came out so low.
 
Thank you for the reassurance - I think that's what I will do. I pitched the yeast in hopes of protecting the hops until I can snag some DME.

I think the gravity issue was from a combination of poor conversion due to insufficient water-grain contact in the mash (might have ended up with a BIAB dough ball) and/or not getting a good enough sparge. Mash temps were within conversion range for the hour so that isn't my primary suspect. Probably didn't help that I was adapting to using new-to-me equipment too.
 
GeologyROCKS said:
Thank you for the reassurance - I think that's what I will do. I pitched the yeast in hopes of protecting the hops until I can snag some DME.

I think the gravity issue was from a combination of poor conversion due to insufficient water-grain contact in the mash (might have ended up with a BIAB dough ball) and/or not getting a good enough sparge. Mash temps were within conversion range for the hour so that isn't my primary suspect. Probably didn't help that I was adapting to using new-to-me equipment too.
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It sounds like you can recover and you know what's wrong, good luck with the fix and your next brew!
 
Are you able post your recipe?
Expecting 1063 and getting 1025 is more than just a little bit of a miss. You did use some DME, and mashed some grains. Makes me wonder if the grains were milled, or whole.
 
GeologyROCKS said:
My OG is about 1.025 instead of 1.063 as expected after putting in my make-up water to bring me to batch size
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The above is what caught my eye. Just to make sure I understand your process: The wort you boiled was a combination of BIAB & DME. Then after transferring that to the fermenter you added water to reach batch size. If so then I suspect that you didn't get the wort and make-up water thoroughly mixed together and your gravity sample was taken from a low-gravity section. You might be closer to your target OG than you think. If you think that's not the issue then do as @Nosybear suggested and boil some DME, cool it and add it in. Whether you are a little high or a little low on OG, you will still be making good beer!

Also, next time take a gravity reading of the BIAB wort, before adding in the DME. That will help determine if the problem is in the mash.
 
BarbarianBrewer said:
The above is what caught my eye. Just to make sure I understand your process: The wort you boiled was a combination of BIAB & DME. Then after transferring that to the fermenter you added water to reach batch size. If so then I suspect that you didn't get the wort and make-up water thoroughly mixed together and your gravity sample was taken from a low-gravity section. You might be closer to your target OG than you think. If you think that's not the issue then do as @Nosybear suggested and boil some DME, cool it and add it in. Whether you are a little high or a little low on OG, you will still be making good beer!

Also, next time take a gravity reading of the BIAB wort, before adding in the DME. That will help determine if the problem is in the mash.
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I did this once with my first extract batch. I topped up with water and then immediately took a sample without giving the water and wort time to mix together. Wound up making my OG reading 10 points lower than it should have been. That'll make you panic for nothing.
If that was an accurate reading I'd have the same question as @Craigerrr , were your grains milled or crushed before the mash?
 
I'm betting that you didn't mix the wort well after adding the top up water and got a very dilute sample. The difference in your gravity reading and expectation is too big for anything else to be probable, provided you didn't make a big measurement error or miscalculation.
 
TL;DR: I may have put the panic cart before the sanity horse and had a bad reading as several of you wonderful folks suggested. The 1.025 is very likely a bad reading since the amount of DME used should yield a higher gravity on its own ignoring the grain. I don't think I've sorted this out but I don't think I missed it as bad as I first though.

Details:
Grist Bill (in pounds) - milled at my LHBS which hasn't done me dirty before.
  • 4.5 Pale 2-row
  • 1.25 white wheat
  • 1 flaked rye
  • 0.75 flaked oat
  • 0.75 carafoam
Total 8.25 (grains) + 4 lbs DME Pilsen Light
Predicted OG: 1.063
Predicted FG: 1.015 (6.3% ABV)
Target Batch Size: 5.5 gallons

BIAB Partial Mash: heated 3 gallons of strike water to 166F; doughed in and dropped to 154F. Mashed for 1-hour in mashtun. Temps dropped but stayed in conversion range. Not sure I got good water-grain exposure in the bag though. Sparged about 1.5 gallons of 170F water by sprinkling over grain bag in the mashtun.

Post BIAB mash gravity came in at 1.035 (temp corrected) with about 3.3 gallons of recovered.

Boiled for about 45 minutes then drew some wort off to mix up the DME slurry. Returned to the kettle to round out the 1-hour boil.

Took a post-boil (grain + DME) reading which was about 1.099 (temp corrected; uncorrected 1.090 at 113F). The volume at this point was about 2 gallons and I brought it up to about 4.25 with make-up water. I stopped to check the SG, which is when I got the 1.025.

Not related to the brew day but certainly took my head out of the game. Shortly after the boil was over I had a valentine's day date with the fire service thanks to a carbon monoxide leak from my house's boiler that tripped the detectors. All is good minus needing a new boiler.

Math
The 4 lbs of DME alone should result in 33 points (1.033 SG) assuming 45 PPG and 5.5 gallons. The 1.025 number is questionable at best and probably due to bad mixing as @BarbarianBrewer, @SabreSteve and @BOB357 suggested. The DME portion of this should be very predictable.

Based on the recipe calculator the grain portion should have provided 30 points assuming 55% brewhouse efficiency (setting used in the recipe calculator). I think I was low here.

I am also suspicious of the 1.099 reading pre-dilution as I would think it should've been higher if I hit the mark.
 
Glad you caught the math issue, I was going to say the 4lb of DME on it's own would give more than what you read.

Probably to late to take another OG reading now but I'd let it buck and see how it turns out. Outside of knowing your ABV there is no real requirement to have gravity readings.
 
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