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Author Topic: I miss my target OG for hi grav beer, what am I doing wrong I think it is sparge  (Read 836 times)

Offline flyingbrewmaster

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I brewed several beers but mainly it is the black ipa in John Palmers wonderful book "How to Brew", Glorious Abyss -Black IPA.  Book specifies an OG of 1.070. I achieved 1.056.  I think it has to do with too much water during sparge.  Rest temp specified to be 150 deg F for 1 hr.  I reached 149 at start, using 6 gal of water at 162 def F (1.5 qrts per lb of malt).  I then raised to 153 after 20 min with 1.5 qrt of boiling water.  After 40 min (20 min after putting in the 1.5 qrts) temp was at 150 deg for final 20 min.  I am using the cylindrical Igloo mash/lauter tun.  After 1 hr passed I sparged out a bit more than 3.5 gal from the initial infusion + 1.5 qrts to raise temp.  I then added 3 gal at 170 deg F and sparged until I reached a bit over 7 gal.  Total load of water was 6 gal of initial infusion, 1.5 qrts after 20 min and then the 3 gal at 170. So of coarse there was significant amount of water left in mash/lauter tun.  9 plus gal to collect about 7.5 gal.  Boil evaporate ~1.5 gal to give me 6 gal to start fermentation.
Does anyone know why my OG (1.056) is so much lower than 1.07 that I aimed for? 

Offline ynotbrusum

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The beauty of batch sparging is that you collect your run off and then decide how much more wort is needed for the boil, because it simply is adding that amount of additional sparge water as the batch sparge.  See Dennybrew for a concise explanation to a popular process - many of us started with his batch sparging for our allgrain beers.

Cheers!
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Offline kramerog

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Sparge water left in the tun results in a loss of efficiency so yes use less water.  The total amount of water you needed is 7 gal (desired boil volume) +16 lbs malt * water retained by malt (~0.1 gal/lb) = 8.6 gallons vs 9.375 so you used a fair amount more of water than needed but not enough to explain even half of your efficiency loss.

The other efficiency killer that I see (it sounds like you were batch sparging) is that you should have been able to run out about 4.4 gallons (6 gallons -1.6 gallons retained by the malt) of high gravity 1st runnings, but you ran out only 3.875 gallons before sparging.

So next time, collect more of the first runnings and use less total water.  As an aside, I would use less strike water (as low as 1.33 qts water/lb malt) rather than less sparge water.

There could be a whole lot of other reasons for low gravity too such as your thermometer reading high especially when shooting for a low mash temperature, grains that aren't crushed by the mill, & not properly mixed mashes (dough balls). I hope that helps.


Offline flyingbrewmaster

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Thank you both for the advice.  It was my first time batch sparging and I will take your advice!

Offline denny

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Did you adjust the recipe to your system's efficiency?  If you were going for 150 and bit 149 I would have left it alone.  For batch sparging info, see dennybrew.com
Life begins at 60.....1.060, that is!

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