Two Low Efficiency Batches in a Row ??

I've been making beer since Jan 2004 - 10 years next month. I've been an AG brewer since 2007 and have made probably more than 100 AG batches. I batch sparge my 5 gal batches using a 48 qt cooler containing a toilet braid. Works like a charm. For the first time ever, I have two batches in a row, made 2 weeks apart, with around 55% efficiency (down from +75%). I cannot figure this out. Here's a little background.

Crush - Each batch was a totally different grain bill (one a Yuengling clone - mostly 2 row; one a hefe which is 65% wheat/35% pils) and from two different LHBSs. So, each batch was purchased and crushed from a different home brew shop. Now, I suppose that both shops could suggenly have 'bad' crushes at the same time but that is highly unlikely. These are the two places I always buy my grains from. Both have always served me well.

Grain weight - each was weighed by me before brewing and both were exactly 11 lb of grain.

Water volumes - I batch sparge and use two 3.75 gallon volume additions using a pre-measured enamel stainless steel pot that I have been using for 10 yrs. This is around a 1.4 qt/lb mash. Not that it matters, but I sparge with around 180oF water. In the past, I've done cool water sparges and I get the same (previously good) efficiencies. Also, there is no residual liquid left in the cooler after batch sparging - the liquid has complete drained. To confirm, after the boil, I end up with around 5.25 - 5.5 gallons in the fermentor and around a quart of material leftover in the whirlpool. This never varies and did not for these two batches.

SG reading error - I cool directly from the kettle through a 30 plate chiller right into the bucket. Although unneccesary, I give the cooled wort a stir when hydrometer goes into bucket so I am quite certain that it is not a lack of wort mixing error. Also, for the hefe I made yesterday, I placed 2 hydrometers into the wort (hoping one suddenly went bad) and both came back the same: 1.044 (where my other 90+ batches read 1.054 - 1.058 for 11 lb grain bills). So, that rules out mixing & hydrometer errors.

Temperature - This is what I thought my problem was a couple weeks ago. So, I borrowed a certified glass thermometer from work (I work in a scientific equipment company and we have lots of labs) and calibrated all my thermometers using 150oF water (as measured by glass thermometer). I found out that my 'trusted' thermometer was 10 degrees low. That made me happy to find that. I also found that one of my other digital thermometers was spot on. So, for this batch, using my calibrated thermometers, I thought my temporary low eff batch was a one off due to low temps and was now in my rear-view mirror. Nope, that wasn't it. Got the same results and I know that my 152oF mash WAS a 152oF mash (as measured in different locations in the thoroughly mash using two calibrated thermometers). For fun, I measured the temp of the boiling wort and the calibrated thermometer read exactly 212oF.

Mash time - I mash for 90 minutes. Always have. I maintain a 90 min mash with NO loss in temps, even in the winter (I cover the cooler with my super-insulated ice fishing jacket). Also, my recently calibrated go-to thermometer is a turkey fryer thermometer. I drilled a small hole in the lid of my cooler a long time ago and insert this long thermometer through the lid and into the mash. I've done this since 2007 and I am confident that this reflects accurate temps.

So, I am at a loss why suddenly, with no changes at all to my brewing ingredients, process, or measurements, I have suddenly lost this much efficiency. I am an analytical chemist by training and as such I fancy myself a decent troubleshooter (I did tech support for 7 yrs) and I understand how to use design of experiments (DoE) to track down cause & effect. Also, I've been reproducibly making beer for some time so I kinda know what I am doing.

What have I missed?

 

Crush is important but if your LHBS hasn't changed anything in their equipment or procedures, you should be fine. I think your sparge water is a little on the hot side for my tastes. Over 176f, the temperature deactivates Alpha Amylase from continuing saccrification. It also enhances the chances of extracting more astringent compounds from the grain husks at that temperature. It's important to make sure that your saccrification rest in your mash and your sparge water aren't exceeding 168f or so. Heck, my strike water for all grain is only 165f..

Aside from that, i'd probably make sure my thermometers were properly calibrated (search for the ice bath method) and keep a 3lb. bag of Extra Light DME around as a safety net, in case you miss your numbers again. I've had to add DME a time or two to save batches. Last time it happened to me, it was a thermometer calibration issue. It happens.

 

I am pretty confident that my temps are now accurate since I calibrated all of my thermometers last week. As I stated above, I calibrated my thermometers using a certified, NIST-traceable, calibrated glass lab thermometer at around 150oF. I, too, suspected temperature as a likely culprit. It may still be, but I don't think so.

Regarding sparge water temps, I do not believe the temp plays much of a role in efficiency as I have also sparged with hot tap water and I noticed zero effects on measured efficiencies. Also, when you add the 180oF sparge water the temp drops down into the 160s. Again, the only reason I heat my water at all is so I don't have to wait as long for the wort to reach boiling.

Thanks for replying. Missing my efficiency numbers is new to me......

 

I'm thinking the likely cause is not measuring your water volumes.

I know you state that you've had no varience in your previous batches without measuring water volumes, but if you're not measuring how much wort you're collecting post-mash or pre-fermentor, then it's impossible to calculate an accurate effieciency.

Based on your values, I'm assuming you're listing brewhouse efficiencies into the fermentor. If that's correct, then it's possible you're not boiling as vigoriously as you have in the past. This would be reflected in substantially lower efficiencies because the sugars present in the wort would not be as concentrated if maintained at a higher boil-off rate.

Bottomline, unless you have measured the volume of wort transferred to the fermentor, you're not really calculating an effiency.

 

Thanks for your reply. However, I disagree that my water volumes are not known/measured. I have calibrated/measured all of my brewing containers. I know EXACtLY how much strike and sparge water I add. I have marked my strike/sparge water pot so I know exactly how much water I am adding. I fill to the 3.75 gal (15 qt) mark, which I know is the correct volume based upon my usual 11 lb grain bill, pre-determined hold up volume in my cooler, grain absorption, and expected boil off volume. I also know I will leave 1 qt in the whirlpool. All of my buckets are marked, and I always end up with 5.25-5.50 gal of wort in the fermentor.

At the end of the day, if I end up with the same amount of wort in the fermentor using the same weight of grains and the same volumes of water and the same brewing equipment, I expect the same OG. That has been the case for many years until just now.

Again, thanks for the reply.

 

Stirring enough during mash? I had a slight drop in efficiency on my last few batches except really bad on my last one, down into the low 60s vs 70-75. I suspect it's because I didn't stir the mash enough. (I'd go get ice for my prechiller during mash time.) Im still trying to figure it out though. I know the crush wasn't very good on the last batch which I think was the tipping point for that one.

Another issue i didn't see mentioned that might be a factor is the pouring back of the vorlauf. If its poured back to quickly you can create channels which will reduce efficiency.

 

Thanks. I'll stir a bit more vigorously at the beginning of the mash and sparge. Can't hurt. I'm actually going to do the iodine test at the end of my next mash. I haven't done that since my first AG batch back in 2007, I think.

With batch sparging you don't worry about channeling since you are not really rinsing the grains. You are re-suspending them in solution.

Thanks again.

 

You go to great lengths to measure temperature, which you yourself admit has little influence on efficiency. However, you don't measure your volumes, which has a much larger impact on efficiency. It just doesn't make any sense.

 

I KNOW what my volumes are, and have for more than 6 yrs. All my containers are marked with volume levels on them. What makes you think I'm making stuff up as I go along? I have (had, I suppose) a very reproducible, empirically-derived process.

Volumes aren't the problem (since I end up with the same volume in the fermentor every time) and would not contribute to more than a (sudden) 20% efficiency loss (1.056 to 1.044).

Merry Christmas.

 

I am taking a stab in the dark here, but are you on a public water supply? I used to have this kind of thing happen when I lived in a house with a public water supply. The county in which I lived would occasionally switch from drawing water from artesian wells to purchasing surface water from a neighboring county. The surface water supply had a radically different chemistry.

 

Good suggestion. However, I am on a well. Haven't tested water since I moved in back in 2005. I suppose it could have changed. Not sure.

Thanks.

 

Your ph possibly, different grains will affect the ph and not really knowing your water profile is not knowing your main ingredient, see if you can test your water again, even city water profiles change all the time due to water consumption, peak season ( summer ) and off seasons (winter) and input it into http://www.brewersfriend.com/mash-chemistry-and-brewing-water-calculator/ along with your grist info, hope this helps

 

You're not making any sense. The OP stated multiple times including in the initial post that he/she is measuring and tracking volumes including final volume in the fermenter and nothing has changed.

Quite the puzzle, that is a pretty huge efficiency drop for someone with so much experience on their system. I'll have to go with the last few suggestions to check the water report/pH. I would think it would have to be a pretty significant change to result in such a drop, though. Not sure if you've read any of Kai's articles on his braukaiser site or if that would help at all. This one on troubleshooting efficiency talks about narrowing it down to conversion efficiency or lautering efficiency, maybe something to consider next.

 

Thanks for the replies, folks. I agree that this is puzzling. I've been so consistent for so long and then two low efficiency batches in a row is really a head scratcher. I'm brewing again on Sat and will really keep an eye on what is going on in my batch, including checking conversion efficiency after the mash and double checking my temps and volumes. I will re-check the pH of my water as well. Next step would be water test.