Question About Batch Sparging and Gravity

Well I finally did my first all-grain brew last Friday after spending weeks studying about it. I converted a 5 gallon Rubbermaid cooler into a mash/lauter tun and planned my first brew for about 11 pounds of grain.

The mash went fine - I pre-heated with 170 degree water and just did a single step infusion at 155 degrees for 60 minutes and 3.5 gallons of water. I then drained the wort and re-circulated it to remove the grain husks. I managed to collect two gallons of wort there and then filled the tun to the top with 170 degree water.

I stirred the grains and let stand for ten minutes before draining this water off. After I finished this drain I had about five gallons of wort and I wanted to get 7 gallons.

Reason for this is that I have to boil with two four gallon pots. I did a test the night before by boiling three gallons of water for an hour and found that I lost a gallon per hour. In my head that works out to 2.5 gallons per pot post boil so 3.5 gallons per pot pre-boil or 7 gallons total.

I then did the same thing again (added hot water, stirred and let stand, re-circulated and drained) and managed to collect 7 gallons this way.

I punched all my numbers in (I took a hydrometer reading from one kettle and used that to calculate my efficiency) and found that I was only 61% efficient. My gravity was also two points higher than what I wanted (1.062 as opposed to 1.060).

Are you still with me? Good... I figured I would lose some people after this long rant. My first question is about how I can batch sparge better to raise my efficiency or should I switch to fly sparging to get 75% efficiency?

My second question is concerning the gravity being higher than expected - is that because of the efficiency being low? I am making a Pale Ale and Pro Mash tells me that 1.060 is the highest gravity for that style of beer according to BJCP.

All-grain is fun but boy is it confusing when you are trying to self-educate...

Did you collect all seven gallons in one pot? Or did you put the first runnings in the first pot, second runnings in second pot, and take a gravity in the second pot? The gravity of second runnings is going to be significantly lower.

I collected the first two gallons of "mash water" and then 1.5 gallons of the first runnings in one kettle and 2 gallons of the first runnings and 1.5 gallons of the second runnings in the other kettle.

The kettle I used to take my hydrometer reading was the kettle containing "mash water" and first runnings. After adjusting for temperature and putting it in the Pro Mash software it spit out 61% for efficiency.

Jesse Seymour said:

I collected the first two gallons of "mash water" and then 1.5 gallons of the first runnings in one kettle and 2 gallons of the first runnings and 1.5 gallons of the second runnings in the other kettle.

The kettle I used to take my hydrometer reading was the kettle containing "mash water" and first runnings. After adjusting for temperature and putting it in the Pro Mash software it spit out 61% for efficiency.

Click to expand...

If I understand you correctly (no guarantees there) the 61% efficiency calculated is in correct. What you told the software is that the sugars you extracted in the "kettle containing "mash water" and first runnings" was all the sugar you extracted from the mash. This is incorrect as you have a second kettle of wort that is unaccounted for.

So far a more accurate efficiency I should have taken two hydrometer readings, one from each kettle, and did the efficiency calculation by hand?

Not only am I new at AG brewing and trying to understand it but I am also new to using Pro Mash which could be a very bad combination.

I know the easy answer is to get a bigger kettle and not to worry about it but with gas prices the way they are that is going to be a while...

Were the procedures I used to sparge with ok or did I do that wrong as well?

Let's say you have 3.5 gallons in each kettle.

If the first kettle read, say, 1.055 and the second read 1.045, it seems you could calculate gravity of the whole by using total gravity calculations.

((55 * 3.5) + (45 * 3.5)) 350 total gravity.
350 / 7.5 = about 47. So your overall gravity would be 1.047 in that 7 gallons.

Now if you're going for 5 gallons into the kettle,
350 / 5 = 70, so 1.070 when concentrated to 5 gallons.

I subscribe to the Bobby M method of mashout/double sparge, or on bigger beers, mashout single big sparge. It, along with a couple equipment mods and a better crush, bumped my efficiency from 66% to 87%.

did you take the reading before or after boil?


The way you sparged sound fine so I think you're ok there.

So for my next batch I would just take the two hydrometer readings using the formula above and tell Pro Mash that I just have a 7.5 gallon boil and use the results of the calculation?

I took a reading prior to boiling and another reading after boiling. I used the reading prior to boiling to calculate efficiency and the one post boil I entered in as the OG reading for my Pro Mash. (BTW, the pre-boil was 1.067 and the post-boil was 1.062).

Using the above example, I would enter 7 gallons and 1.047 for my gravity to have it spit out an efficiency of 84%.

So it looks like the odds are pretty good that I hit at least 75% efficiency because my hydrometer read 1.067 in the first kettle so if I assume (because I did not measure) that the hydrometer would be half for the second kettle, or 1.033 I can feel good about guessing that my efficiency was 89%.

CrackyMcZap said:

Let's say you have 3.5 gallons in each kettle.

If the first kettle read, say, 1.055 and the second read 1.045, it seems you could calculate gravity of the whole by using total gravity calculations.

((55 * 3.5) + (45 * 3.5)) 350 total gravity.
350 / 7.5 = about 47. So your overall gravity would be 1.047 in that 7 gallons.

Now if you're going for 5 gallons into the kettle,
350 / 5 = 70, so 1.070 when concentrated to 5 gallons.

I subscribe to the Bobby M method of mashout/double sparge, or on bigger beers, mashout single big sparge. It, along with a couple equipment mods and a better crush, bumped my efficiency from 66% to 87%.

Click to expand...

Thanks for the correct math McZap! I couldn't get my pre-caffinated mind around it.

Could you provide details on the Bobby_M method for larger beers?

Thanks!

Everything you ever wanted to know about my all grain technique can be found in the link in my sig. I believe what Mczap is talking about is adding just a smallish amount (1 gallon perhaps) of hot water to the mash prior to first runnings because a small MLT with a large grain bill usually doesn't have enough room for large sparge infusions.

Bobby_M said:

Everything you ever wanted to know about my all grain technique can be found in the link in my sig. I believe what Mczap is talking about is adding just a smallish amount (1 gallon perhaps) of hot water to the mash prior to first runnings because a small MLT with a large grain bill usually doesn't have enough room for large sparge infusions.

Click to expand...

Thanks Bobby. There was a LARGE thread last week going over the batch sparge technique. I couldn't remember any special treatment for big beers though. I'll reread your all grain primer.

The method I used for my latest brew is a slight modification of Bobby's technique.

I have a 7-gallon MLT, and I did a two step infusion mash (140, 154) with 15.5lb of grain. I wanted two runnings of about the same volume (3.75 gallons each) so I calculated the mashout to get me up to about 170 and to the correct volume to get about half my pre-boil volume with one running. Then I sparged with another batch of 170 degree water to get another 3.75 gallons and ended up with 5.5 gallons after the boil.

Of course my dumb self forgot I had the recipe set for 66% so I ended up with an oatmeal stout with OG of 1.078. That's all good for me though, since it's my beer and I like to push the limits anyway. We don't need no stinkin' style guidelines :cross:

It's reassuring to hear that my sparge procedures sound good to more experienced brewers... that was my biggest worry with this last batch.

Since I pitched this batch, the lag time was 14 hours and the airlock bubbled for one day. I am going to take a hydrometer reading on Friday and see what the current gravity is.

Does anyone know of any good promash tutorials? I'm not dead sure that I am putting the right numbers into it to get good information back out...