Batch Sparging for Dummies, Episode 3

[quickerNu]

For all those who have helped, thanks! Here's my update after AG attempt #5, Edwort's Haus pale again
8 lbs 2 row, 2 lbs Vienna, .5 crystal 10.

This go around I used 1.3 qt per lb for 13.65 qt- 3.4 gallons. I used HEB "drinking water" charcoal filtered, oxygenated for 3 gallons, and tap water for the other .4

My first runnings (after a 60 min mash) collected 2.25 gallons at 1.076 draining slowly vs my old method of draining as fast as possible.

I sparged with 4.3 gallons, roughly split into 2 batches. brought bed to 168, stirred, let sit for 10 minutes, vorlaufed and ran off slowly for 1.040.

After all was drained, I poured in the other half, stirred vourlaufed, the ran off slowly. 1.020

I only measured the volume of first runnings (2.25) and figure I can safely assume all sparge water was recovered for a total into the boiler of 6.5 gallons. I measured the SG here, and was at 1.041

After a 1 hour boil, I cooled, then whirlpooled, then racked first to my jug for a sample, then to my primary. Is there a possibility of post whirlpool wort having a different SG at different depths? Next time I will measure OG after racking and thoroughly mixing in the primary just in case, because my measured OG was only 1.044. That seems a little low after boiling down from 1.044 @ 6.5 gallons to a hair over 5 into the primary (maybe 2 cups of trub and wort left in the boiler).

Could my OG measure have been inaccurate because of measuring from a post whirlpool boil pot instead of a thoroughly mixed primary?

 

[Joe Camel]

Here's some very "notes on a napkin" type calculations, I can't speak to their accuracy, but they might help

10lbs of grain at 36ppg and .5 at 35ppg = 377.5 total points of gravity in the mash

3.4 gallons of water plus about .8 gallons of grain volume in the mash = 4.2 gal

377.5/4.2 = 89.9, so your first runnings gravity should be around 1.090, yours was 1.076, or about 84.5% efficient in the mash.

377.5 * 84.5% is about 319points of available sugar in the mashtun.
Your lauter numbers were:
2.25 * 1.076 = 171
2.15 * 1.04 = 86
2.15 * 1.020 = 43

total is 300 points in 6.5gallons, give or take due to inherent errors. 300/319 is 94%, pretty good lautering efficiency, 300/6.5gallons is 44, so your measurment of 1.041 is pretty close to 1.044 that I calculate. 1.041 is still 87.4% efficient, pretty good. The total mash efficiency is a product of the two calcs, .845*.874 = 73.8% into the boiler. Out of the two efficiencies, you might get more mileage out of getting a better mash number, if you get full conversion in the mash, your total efficiency into the boiler jumps to 87.4%, a gain of 13.6%.

That all having been said, your OG in the fermenter should be around 1.056
with the boil off, so there is something weird going on.

Solutions that are boiled that long should have no gradients forming so I don't think the issue is there. I remember you saying you wait until the samples are below 90F before reading sg, but are you correcting for temperature after taking your SG readings?

 

[Dr Vorlauf]

You should be using more sparge water than mash water.

+1 I just made the mistake of not using enough sparge water last weekend and I know better. Ruined my efficiency and left me low on IG.

 

[quickerNu]

Thanks Joe. I am correcting, and have measured the temp at several levels in the sample tube. The first runnings were 2.25 gal, though. Damn I need to figure out my software. I plunge the hydrometer up and down several times and measure temp at several depths to make sure they are consistent. I guess I need to make another batch- pratice makes perfect!

 

[Joe Camel]

well, unless you have a leak in your boiling pot, all the sugar you put in should be there, maybe there was water in your sampling jug when you took your final SG before primary and it's diluting that read.

 

[haish]

Is your hydrometer accurate? Have you tried measuring distilled or RO water? Sometimes the scale can slip giving inaccurate readings.

Otherwise try reading at the correct temperature rather than correcting. I have found that compensating for temperature doesn't always work out to the correct gravity reading.

 

[Bobby_M]

I would have suggested that your preboil gravity sample was skewed due to gravity gradients in the boil kettle initially but since you took measurements of each running, the numbers add up (close enough). There's no way 1.041 would only boil down to 1.044 though unless you never really acheived a rolling boil. What did you get for a final volume into the fermenter?

 

[quickerNu]

Final volume into the fermenter was just a hair over 5 gallons. I never have to correct more than 1 point for temp.
Bobby, I am also thinking of how much star san was in my autosiphon and hose. I start the siphon into my test cylinder, then to fermenter. Maybe there was enough in there to throw off my og reading, if you think all the pre-boil #'s add up. Maybe this beer will have a bit more kick than I originally thought.
It was a good solid boil, going from about 6.5 to less than 5.5gallons

 

[Kauai_Kahuna]

quickerNu - Sounds like your getting pretty good numbers, and I agree that either you had some layering or some extra water in the final reading. It sure sounds like you have things dialed in.

 

[Joe Camel]

Occam's razor man, I'm leaning toward the simplest answer... water in the siphon. Wait until later in the rack to draw the sample and all will be well.

 

[eurc51]

wildwest450 - can you recommend some software? I found a free evaluation copy of ProMash - is this a good source?

euRC51