Sparging with digimash

[adam01]

First session using digimash - for mashing. I brewed an oktoberfest with a target gravity of 1.047 before boil. The recipe, from beersmith, specified 21qts mash water and 8qts sparge water. Sparge went quite quick - too quick in my opinion and I was unable to track the gravity as it went.

I ended up with 1.040 gravity with 7.2 gals. I don't think the sparging went well as the drippings from the malt pipe were quite high in gravity (1.016) after sparge was done. This seems to indicate a 65% efficiency of the mash. I was targeting 76%, not knowing what to expect.

Besides creating a manifold for the sparge and slowing it down, what do others do to achieve reasonable (closer to 80%) efficiencies ?

thx

 

[doug293cz]

First session using digimash - for mashing. I brewed an oktoberfest with a target gravity of 1.047 before boil. The recipe, from beersmith, specified 21qts mash water and 8qts sparge water. Sparge went quite quick - too quick in my opinion and I was unable to track the gravity as it went.

I ended up with 1.040 gravity with 7.2 gals. I don't think the sparging went well as the drippings from the malt pipe were quite high in gravity (1.016) after sparge was done. This seems to indicate a 65% efficiency of the mash. I was targeting 76%, not knowing what to expect.

Besides creating a manifold for the sparge and slowing it down, what do others do to achieve reasonable (closer to 80%) efficiencies ?

thx

Couple of questions:

• What was your grain bill?
• Does the Digimash have a malt basket (perforated sides) or malt pipe (solid sides) to hold the grain?

To diagnose your mash efficiency you need to separate out your conversion efficiency (how much of the available starch did you convert to sugar?) and your lauter efficiency (how much of the actual sugar did you get into your boil vessel?). Mash efficiency = conversion efficiency * lauter efficiency. The causes and cures when either of these are low are different, so you have to know which of the two is abnormally low so you know which one needs to be fixed and what might need to be done.

You also need to collect accurate grain weights, water volumes, wort volumes, and SG readings. You should measure the SG at the end of the mash (prior to sparging) after homogenizing the wort well, as the grain bill, strike volume, and end of mash SG can be used to calculate your conversion efficiency. To calculate your mash efficiency, you need the grain bill, pre-boil volume, and pre-boil SG, or the grain bill, post-boil volume, and post-boil SG. Lauter efficiency is calculated as mash efficiency / conversion efficiency.

You say you mashed and sparged with 7.25 gal (29 qt) of water, and say you collected 7.2 gal pre-boil. For a 10 lb grain bill, that would calculate to a 0.005 gal/lb absorption rate. Since a typical basket absorption rate is about 0.12 gal/lb, at least one of your volume measurements has significant error, and the measurements are inadequately accurate for the task of estimating efficiencies.

So, your first task with your next brew is to make sure you are taking all off the measurements above, and improving the accuracy of your volume measurements (these are usually more problematic than grain weight or SG measurements.)

Brew on

 

[adam01]

malt pipe is solid, no perforations

11lbs grain.
21qts in mash (13:11 ~ 1.2:1) + 8qts under mash pipe
8 qts sparged
total 29 qts = 7.25 gals actual 1.040 SG vs beersmith est 1.047 SG

Before digimash recipe
13.8 qts for same grain (1.3gal absorption from beersmith)
4.3gals for sparge 1.050 SG
est mash efficiency 75%
6.5 gals wort

I guess I should recirculate for several minutes before sparging to equalize the SG.

The BIAB mash profile of beersmith suggests this:
30 qts in mash
est mash 1.047 SG efficiency 80%
est 6.9 gals
With the BIAB setting, and 6.9 gals of wort, I will need to boil for longer to get down to 5.5 gals.

 

[doug293cz]

malt pipe is solid, no perforations

11lbs grain.
21qts in mash (13:11 ~ 1.2:1) + 8qts under mash pipe
8 qts sparged
total 29 qts = 7.25 gals actual 1.040 SG vs beersmith est 1.047 SG

Before digimash recipe
13.8 qts for same grain (1.3gal absorption from beersmith)
4.3gals for sparge 1.050 SG
est mash efficiency 75%
6.5 gals wort

I guess I should recirculate for several minutes before sparging to equalize the SG.

The BIAB mash profile of beersmith suggests this:
30 qts in mash
est mash 1.047 SG efficiency 80%
est 6.9 gals
With the BIAB setting, and 6.9 gals of wort, I will need to boil for longer to get down to 5.5 gals.

"21qts in mash (13:11 ~ 1.2:1) + 8qts under mash pipe" is that 21 qts total in mash or 21 + 8 = 29 qt in the mash?

Was 6.5 gal you actual pre-boil volume?

Assuming 11 lbs of grain at an average potential of 1.037 and 4% moisture, with 5.25 gal of strike water, your end of mash SG (before any sparging) should have been about 1.066 at 100% conversion. Your combined wort after sparging should have had an SG of about 1.054.

With a solid sided mash pipe, recirculation will not homogenize all of the wort. The zone between the malt pipe and vessel wall is a dead zone for flow, and does not get mixed by recirculation (unless you do something specific to make sure some of the recirc flow goes thru this zone. The easiest way to make sure your wort is homogenized in the case of a solid malt pipe is to raise, drain, and lower the malt pipe several times. However, this doesn't work well if you have a loose FB which can float up when you lower full malt pipe.

The problem with the dead zone is that the wort there is very dilute, which means the wort in and under the malt pipe is more concentrated, and that is the wort that gets absorbed and retained by the grain. More sugar retained by the grain will lower your lauter efficiency, which is why you want to homogenize all the wort before lautering.

Brew on

 

[tracer bullet]

raise, drain, and lower the malt pipe several times

Completely agree. We Anvil Foundry users call it "lift and lower". Do that every 15 or 20 minutes and you'll see a huge bump in efficiency.

Anvil has .9X gallons of dead space under the pipe, but it tends to mix in. There's 25 - 30% of the cross section of the rest that's also dead space that does not mix in without, as mentioned, extra work.

Typically no big deal, I like to walk away for the mash but it's not a bad idea to come back and check a few times just to be sure something didn't start to come out of the unit and begin to cover your counter or floor.