Efficiency Puzzle

[arakow]

I have been brewing with a converted 5 gallon Rubbermade cooler with a domed false bottom for several batches now and I have had low efficiencies (averaging around 58%, but as low as 55%). I am trying to figure out why.

I fly sparge SLOWLY, usually with 180F water after vorlauf and make sure that the grain bed stays under at least an inch of H2O and I shower it very gently with a sparge arm.

I tend to use 12-13.5 pounds of grain. The only thing I can figure is that in this (small) size cooler, this much grain is resulting in too tall of a grain bed that is getting compacted and is not loose enough and that is what is resulting in my low efficiency. I haven't had any stuck mashes, but they do seem to draw slowly, even if the ball valve at the bottom of the cooler is opened wide.

Is there anyone out there with thoughts about this? I've been stumped trying to figure out what I might be doing to result in lower efficiency. I have checked with others brewing from the the same shop and they are doing fine with the grist that's milled there, so I don't think that's a culprit.

Anyone care to opine? Thanks!!

 

[The Pol]

I have been brewing with a converted 5 gallon Rubbermade cooler with a domed false bottom for several batches now and I have had low efficiencies (averaging around 58%, but as low as 55%). I am trying to figure out why.

I fly sparge SLOWLY, usually with 180F water after vorlauf and make sure that the grain bed stays under at least an inch of H2O and I shower it very gently with a sparge arm.

I tend to use 12-13.5 pounds of grain. The only thing I can figure is that in this (small) size cooler, this much grain is resulting in too tall of a grain bed that is getting compacted and is not loose enough and that is what is resulting in my low efficiency. I haven't had any stuck mashes, but they do seem to draw slowly, even if the ball valve at the bottom of the cooler is opened wide.

Is there anyone out there with thoughts about this? I've been stumped trying to figure out what I might be doing to result in lower efficiency. I have checked with others brewing from the the same shop and they are doing fine with the grist that's milled there, so I don't think that's a culprit.

Anyone care to opine? Thanks!!

I used to have a 5 gallon cooler MLT, never had this issue. How is your water composition? Are your thermometers accurate? Ever taken a mash gravity reading to determine the conversion eff?

http://braukaiser.com/wiki/index.php?title=Image:First_wort_gravity.gif

 

[sudbuster]

[What's going on with your conversion process? Temps, time etc?

 

[arakow]

To give you an example, I just brewed a batch with 13.5# of grist. I preheated the cooler MT with 125F H20 and dumped that before adding 3.75 gallons of H20 at 173F to the cooler. I carefully floated/stirred in the grist and let it sit. I then took a temperature reading with a 12" long thermometer from a turkey fryer and it read 150F. I let the mash sit for 60 min before sparging. I did not do a conversion test. The gravity of the first runnings was just over 1.080. I collected 5 gallons of wort from fly sparging with 180F H20 for about 1.5 hrs. The gravity of the 5 gallons after collecting it all was about 1.044.

I haven't checked the thermometers that I use to make sure they're accurate. The 12" long turkey fryer one is a POS I have to say. I'll check that next...

 

[ajf]

You say you sparge slowly. How slowly? With similar equipment, it would take me about 60 minutes to sparge 10# grain, or 90 to sparge 13.5#
Pol's suggestion about measuring the mash efficiency is a good one, as it will help to isolate where in the process you are losing efficiency.
Do you do a mash out? When I started doing this, my efficiency jumped by 10%.

-a.

 

[The Pol]

FWIW, I do a mash out... that being said, when I didnt do one my eff. was still 78%.

It takes me 40 minutes to sparge a 12lb grist

You really need to check your conversion eff. This will tell you if you have a problem in the mash, or if it is in the lauter. It is typically heavily weighted on one or the other.

 

[arakow]

I have a mash thickness of about 1.1 qt/lb. When I checked the first wort runnings from the last batch, it was just over 1.080. This isn't close to the gravity that's listed on the chart that "The Pol" forwarded (thanks!):
http://braukaiser.com/wiki/index.php?title=Image:First_wort_gravity.gif

This seems to indicate something's up with my conversion. I just got back from the brew shop and got some pHydrion papers to check the pH coming out of my hose. It appears to be at least 6.0. The scale stops at 6.0 on the dark end and the paper is reading darker than the scale. I then pulled up our city's water quality report. The pH according to the report is 7.7-8.8. Of course, this doesn't tell me anything about what the mash pH is, which is the real concern.

I don't know how 7.7-8.8 compares to other municipal supplies. This sounds like it could be high (alkaline) to me...?