Gravity too high for sparge water

[CascadiaHB]

Hey all, first official post here.

Im trying to get an idea why my sparge gravity wont drop like it should. My sparge water runoff repeatably is around 1.030 as measured with a refractometer and a hydrometer.

I work off a 1bbl system and sell the beer by the pint. Each recipe is a one of a kind, no flagship beers here.


Here is a typical recipe/volumes...

92 lbs grain
Protein rest at 120*F (70qt water)
Sac Rest at 152*F (add 44qt boiling water)
Rest for 1 hour
Fly sparge with 100qt water at roughly 170*F

On my smaller systems I have used in the past there was never a issue with the sparge water, it usually dropped down to 1.010 by the end of the sparge. I check the temperature every 15 minutes and give it a good stir. It takes a little over one hour to run the fly sparge. I get about 40 gallons into the boil kettle and 36-38 into the fermenter.

I maintain the temp of my sparge water during the 1 hour. The real issue is my efficiency is lower than it should be and I feel like I am converting the sugars but just not pulling them out of the grain bed

Equipment:
42 gal mash tun with false bottom
75 gal boil kettles


Chris

[jebzter]

What is your mash efficiency? You could be sparging too fast, though it doesn't sound like it. Do you vorlauf? Are you hitting your target gravity for the beer pre-boil and post boil? Sounds like you have a major efficiency problem, but without more knowledge of what all of your processes are.

[CascadiaHB]

Yes I do vorlauf with the pump on slow.

My efficiency is lower than I have ever dealt with and I have been brewing for 12 years. They are somewhere in the mid 60's to lower 70's for the mash efficiency (going up slightly higher with each batch) My final brew house efficiency is in the low 70's. Mash temperatures are on target, beer is running clean and overall I am very happy with the product (and so are the customers) but I feel like I am wasting a lot of grain. I have been struggling a little with the mash pH, it is sometimes right on target, 5.2, while other times it goes up to about 5.6 but never much above that.

One thought is that my grist ratio is a little on the lower side, usually 1.3:1 (qt:lb of grain). My mash tun size is definitely my limiting factor.

I had not stirred while fly sparging in the past but that was a smaller system, is it needed on larger systems?

[millerag]

Mash Tun

What is the geometry of your mash tun? What is the height to width ratio? The mash tun we use was wider than high and when the mash depth got deeper we got better efficiency. How about your crush?

[CascadiaHB]

millerag,

it is about 25" x 22" (height x diameter).

As far as the crush it is hard to tell what the ideal crush is. The kernel is broken into 2-4 pieces and the husk is usually split in half. it seems pretty good to me but there is no easy way to test the grain crush without brewing up a lot of test batches

[AT-JeffT]

What gravity are your first runnings?

[CascadiaHB]

with the example given above it was around 1.075

[jebzter]

Why not run some test mashes with progressively finer crushes until the run off starts to slow. Its a lot of grain to go through, but you will know where to set your mill at that point. You can get some sieves to figure out the various percentages of fines, course and husk, but that doesn't do you any good until you know where you want to be.

[mswebb]

When you are sparging, what temperature does your mash reach? With low efficiency in the mash and no specific mash out step, you might be sparging too slowly and continuing your conversion and extraction. Optimally, you want to reach your target for mash gravity (first wort runnings) then lock it in by raising the mash temp and denaturing your conversion enzymes (mash out). With the mash locked-in, your sparge will not create more sugars, just wash down what you have already converted.

[CascadiaHB]

That was one of my thoughts too. My mash tun is too small to add in more water for a mash out step. I could pull off my first running, boil it and then add it back in to kick up the temp.

I think I might mess around with the grain crush and see if that helkps out. Does anyone know of a good thread that talks more about honing it in or maybe have some good pictures?

[Bakes]

We had similar issues going from our pilot to our 6hL brewhouse with low efficiency, but soon tweaked it to get efficiency back up into the 80's. Looks like you've got a similar issue.

Your strike to sparge ratio is around 1.14 (114qt in protein and sac, 100qt in fly sparge). We were running a similar number initially but cut our grist ratio back from 2.5L/kg to as low as 2.0L/kg (which is roughly 0.8qt/lb if I've done my conversion right). That allows more strike water to run through your mash and decrease the extract left in your mash, resulting in higher efficiency and should get your final runoff cost to 1.010.