1.005 Runoff, expected efficiency, but low pre-boil volume?

[breckenridge]

The last two times I've fly sparged, I've had the same problem: my pre-boil volume is 2-2.5 gallons short (10 gallon batches), I catch the runoff well below where I'd like to have stopped collecting, but the collected wort is higher gravity than I expected, and there's still 2+ gallons of diluted liquor in the MLT.

The dilute wort was low pH, so I'm hopeful that I'll avoid astringency in this batch, but frustrated that the volumes aren't coming out as expected.

I'm using BeerSmith 2, set to Blichmann 15 gallon profile (what I'm using, except a 20 gallon boil kettle).

A couple weeks ago when this happened, I just went with the lower volume, higher gravity boil (old ale). Yesterday, I added filtered water to make up the pre-boil volume. Everything came out right after that (well, higher than expected efficiency, but I can live with it). I didn't treat the diluting water with Campden tablets as I did the HLT and mash water, thought.

Anybody have an idea WTF I've miscalculated here? I don't recall this happening before, though it's been a few months since I brewed last. I'm about to bag it and just go back to batch sparging.

Brew was a dry Irish stout, 17.5 lbs grain, about a 5" grain bed in the MLT, running off at about 1-1.5 qts/min, expected pre-boil volume 14.5 gallons of 1.035 wort, actually 12 gallons 1.045 wort.

Thanks for any help if you all can solve this. It feels like an algebra problem that I just can't wrap my head around for some reason.

 

[Double_D]

If you're short on boil volume and your pre boil gravity is too high then you're under sparing. Why aren't you sparing and collecting wort up to you target pre boil volume? 14gal at .035 is like a3.5% beer...the gravity on the runnings will be low because of the beer you're making.

What is your boil off per hour?

 

[breckenridge]

Boil off is 2.5 gallons over 90 minutes. 0.5 gallons lost to trub/chiller, 0.5 gallons per carboy lost to yeast cake, plus cooling shrinkage.
Actual OG was 1.050 for 11 gallons collected when all was said and done.

Final runnings below 1.010 is not recommended due to concerns about extracting tannins and other undesirable flavor compounds, hence why I arrested the sparge before collecting the expected volume.

 

[chickypad]

I think you're just making a fairly low gravity/small grainbill beer with a fairly big target boil volume, boil off loss, etc. If you had topped off your 12 gal to 14.5 with water sounds like you'd hit your numbers. So I would just go ahead and do that, or try to cut down some of the losses. For example I see no need to boil an Irish stout 90 min, so that will cut off about .8 gal there.

 

[breckenridge]

I do 90 minute boils for everything just so I don't have to adjust for when I really need to do it. Feels easier, an article on this site convinced me, and I've been doing it for a good year now with no issues (other than having to get propane more often).

Also, the same thing happened with a 1.076 old ale, so it's not unique to low gravity beers.

 

[chickypad]

So you got that same high efficiency on the 1.076 beer? Looks like over 85% on the first one. If your efficiency wasn't so high I'd think maybe channeling. But you're hitting the numbers, what's the problem with just topping up?

 

[Qhrumphf]

How about simply mashing a little bit thinner initially, and let it drain down a bit before you start sparging? Not sure if it'll work, and I'm too exhausted to reason through it fully, so if someone has a better idea (or reason why that wouldn't work), by all means.

Or, like suggested above, if the sugar content is already where it should be, then just top up the kettle with water. Better to add no sugar content and end up where you should be than to continue sparging, maybe end up a touch high, and pull tannins and phenols you don't want.

 

[acidrain]

Do you have your boil off and other losses dialed into your equipment profile in Beersmith? Maybe a screen shot of your equipment profile would help us see if anything is off/missing.

 

[breckenridge]

Main problem with topping up is chlorophenols in my water. I triple-filter, but don't have a spare supply that has been treated with Campden tablets for topping off.

I'll try to post a screenshot of the equipment profile later today or tonight.

Mashing thinner was suggested by someone replying on my tumblr, and makes good sense to me. I had mashed at 1.25 quarts/lb, will try it at 1.5 qts/lb this weekend on my APA.

Boil off and losses to trub and chiller are definitely dialed in, as I believe dead space is, to within a pint anyway. I will re-check volume of pew-BK losses this weekend, too.

 

[chickypad]

Main problem with topping up is chlorophenols in my water. I triple-filter, but don't have a spare supply that has been treated with Campden tablets for topping off.

I still don't get it, can't you just run off 2.5 gals into a bucket either filtered or treated with campden then top off your boil kettle?

For comparison it does look like you do a lot more sparging compared to my system. I also have a 20g Blichmann kettle, just ran some numbers in BS. Some differences are I tend to use about 1.5 qt per lb mash thickness and target 13 g boil volume. So to get 11 gal of 1.050 beer into the fermenter I would be collecting 4.75 gal of first runnings and fly sparge with 8.25 gal. Assuming .125 gal per lb absorption looks like you got more like 3.2 first runnings and sparge with 11.2 if you were going all the way to 14.5. Add to that you're efficiency is a little higher than mine (I'd be doing this with 19 lb of grain) seems like it does explain your numbers. At least I don't see anything you're doing wrong in the actual calcs.

edit: corrected typo on absorption rate

 

[breckenridge]

So, I *should* have had some campden pre-treated water ready, I guess. Didn't expect this a second time, though, and ended up just using filtered water to top off, and all was well, just with better efficiency than expected.

Hoping it will be fine, but paranoid because I had a red rye ale a year or so ago that I ended up having to dump because of chlorophenols. Not sure if rye brought out that flavor more, or variation in our water supply made it more pronounced, or what. (I also know that I didn't use Campden tab on that batch, so..)

Anyway, mashed in 1.25 qt/lb as I said, with 17.5 lbs grain, and sparged with a little over 8.5 gallons water.

Braukaiser and Palmer both seem to say that a somewhat higher water-to-grist ration will aid efficiency, too (not my concern, but always a nice bonus).

Palmer also suggests a ratio of sparge water to mash water of 1.5, which is even more than what I had used previously. I won't be going that route this time.

I'll update with results this weekend.

Thanks again, all.

 

[breckenridge]

Update:

Brewed today using 1.5 qts/lb in the mash, and hitting my efficiency numbers pretty much right on track. Final runnings were 1.008, with only about a quart left in the MLT.

Many thanks to those who offered suggestions on this issue. I'll be using 1.5 qts/lb going forward. I wonder if a BS software update changed the default to 1.25 or something? I don't remember ever having this issue before a couple of months ago.

Regardless, fixed now, so the only issue is what to brew next!

 

[Qhrumphf]

Update:

Brewed today using 1.5 qts/lb in the mash, and hitting my efficiency numbers pretty much right on track. Final runnings were 1.008, with only about a quart left in the MLT.

Many thanks to those who offered suggestions on this issue. I'll be using 1.5 qts/lb going forward. I wonder if a BS software update changed the default to 1.25 or something? I don't remember ever having this issue before a couple of months ago.

Regardless, fixed now, so the only issue is what to brew next!

I used to mash at 1.25, then realized I get more consistent, better results, easier lautering, easier mash mixing, more stable temp, basically everything is better at 1.5. Only downside is that with the alkalinity of my tap water (by no means extreme but enough to require treatment), it requires a slightly higher relative amount of acid to keep the pH in the right place. Which in my book is barely a concern.

So I do that for absolutely everything, unless space dictates otherwise (and I seldom brew a beer big enough to force the space issue unless I'm doing a partigyle or a 10 gallon batch).