What is “mash gravity”? As in, take a sample straight out of the mash tun before any sparge water is added, or before anything is drained?
I have taken a sample of the first sparge (what I interpret by Kai’s spreadsheet reference to “first runnings”), and his spreadsheet reports me off by 15%, assuming that belgian 2-row, belgian caramunich, and belgian special B all have the “default” 80% extract potential.
I interpret “1st runnings” to mean the liquid you collect when you drain the mash the first time (pre sparge when batch sparging). I’d drop a hydrometer in 1st runnings at room temp (better yet 60* F) to get mash gravity.
[quote=“BcuzI’minUT”]You are measuring your gravity after the boil (and cooling), right?
I’d also ditch the refractometer (for now) and use a hydrometer instead. You should also check your hydrometer at 60F in distilled water. I have two hydrometers and both are a little off in the opposite direction.[/quote]
[quote=“Silentknyght”]
Yes, measuring OG after chilling, before pitching yeast. Why ditch the refractometer? Just superstition? It’s easier to use than my hydrometers.[/quote]
Two reasons: (1) You are relying on the accuracy of the refractometer but cannot confirm that it is giving you correct measurements; (2) I’ve used my refractometer side-by-side with my hydrometer and regularly saw wrong numbers from the refractometer.
That’s just my experience.
Oh, are you also getting good post-cooling volume measurements? Obviously, this can throw off efficiency measurements. Finally, you might consider inviting over an experienced all-grain brewer on brew day. Maybe you are doing something on brew day that you haven’t even mentioned, which is causing lower efficiency. It seems like I frequently read “what am I doing wrong?” posts only to read a “solution” post that it completely different from the original post. For example, maybe you have huge dough balls in your mash. Anyway, just a thought. Good luck!
[quote=“BcuzI’minUT”]I’ve used my refractometer side-by-side with my hydrometer and regularly saw wrong numbers from the refractometer.[/quote]If you use a correction formula to convert the refractometer reading to SG (which accounts for the presence of non-sucrose sugar in the wort), then the pre-pitch readings should be exactly the same. If not, then there is likely a calibration or an instrument reading error.
I guess maybe that’s my point (as I think some others have alluded to), which is: get back to basics and eliminate as many variables as possible, i.e. ditch Beersmith in case the defaults are not set up correctly, find formulas for calculating water volumes and plug in the variables and not rely on some calculator on some website, use a thermometer that’s been checked in ice water and boiling water and not one of the those laser things, use a hydrometer that’s been checked in 60 degree distilled water, don’t rely on volume measurements on the side of brewing buckets, and so on.
And again, I think he needs to invite over a brew buddy to watch his steps. So many times I read posts where we are doing the equivalent of trouble shooting a car that won’t start but no one checked to see if there was gas in the tank before the whole engine has been disassembled and reassembled a dozen times. (Of course, now we all know how to take apart an engine when the time comes!)
Anyway, happy brewing and good luck!
[quote=“Silentknyght”]
What is “mash gravity”? As in, take a sample straight out of the mash tun before any sparge water is added, or before anything is drained?[/quote]
Mash gravity and first runnings is equivalent. I’ve just always called it the mash gravity - i.e. the gravity of the mash after conversion before any liquid is removed from the tun.
Being off by 15% is surprising with that mill gap. Like Shade said it could be mash pH. Another thing that would be worth experimenting with is bringing the mash temp up above 160°, and see if the mash gravity reading changes. This could indicate you are mashing too cold. After doing this measurement on about a dozen batches, I saw anywhere from 0 to 2°P difference after doing this ‘mashout’, most were around 1°P. I just do it every time now because it’s easy for me to recirc through the HLT, YMMV.
As for how the measurments are done, I think you understand how the accuracy of things like the volume measurement affect the final result, 1 qt of inaccuracy can be about 3% of calculated efficiency in a 5 gal batch. When measuring gravity of hot wort, it’s important to cool the sample to room temp first in a sealed container. I use a 1 mL syringe for refracto samples, just throw it in the freezer for 5 min. Putting a hot sample on the lens with significantly distort the reading due to evaporation (it reads higher than reality). The difference is less the faster you close the lens, but it’s best practice to just cool it down first for consistency in the reading.
If you have some data you’d like to share on a batch, I can double check your numbers. I would need grist composition and mash water volume. We can also check the full batch efficiency if you have the sparge water volume as well.
This is a good point; when using a refractometer you need to keep evaporation from affecting your reading. I take my samples in an eyedropper, and have found that I need to discard 2-3 drops from it before I place the two drops I measure on the glass. Even with the tiny surface exposed at the end of the eyedropper, you can see a measurable concentration of sugars due to the evaporation that takes place.
Interesting point. I’ll be brewing again next weekend… I’ll try this, and I’ll record all my data again for sharing.
EDIT:
For what it’s worth, here’s the data I had on the latest recipe:
11 lbs Belgian Pale Malt
8 oz Belgian caramunich
4 oz Belgian Special B
Conditioned with 3 oz lukewarm tap water
Double-crushed at 0.028 to 0.030".
As recommended by Bru’n’water, added 2g gypsum, 1g CaCl to the (dry) mashtun to adjust for pH due to the “Fridley” water
, which was 25%, with 75% RO. Mixed all batch & sparge water together in one pot, to mix, and decanted to other pots to acquire strike/sparge volumes.
Added 4.4 gal strike at 174F to the (dry) mashtun. Added grains & stirred; few to no doughballs. Temperature was 158; stirred for a few minutes down to 154 (target temp) & lidded the tun. A pH sample cooled to 111F read 5.25.
Mashed 75 minutes. Temperature at the end was 153.
Added 0.5 gal 190F sparge water. Stirred mash, vorlaufed 2 liters, and drained to kettle. An uncooled gravity reading taken 15 seconds after draining to kettle read 15.8 brix. A second, uncooled gravity reading taken at the end of the end of the first sparge read 16.4 brix. After a few minutes, some water was still standing, barely (if that) moving on the top of the grains in the tun, so I tipped the tun forward.
Added 3.5 gal 180F sparge water (had cooled a bit). Stirred mash, vorlaufed 1 liter, and drained to kettle. Tipped tun again, but to a lesser degree. Pre-boil volume (at ~150F) was 7.1 gal. Preboil gravity readings were 11.6 and 11.9 brix.
Boiled. Added 1 lb candi sugar.
Postboil volume into fermenter was 6 gallons. Gravity, measured @ 75 degrees, prior to racking to fermenter, was read at 14.2, 13.8, 14.4 brix (3 readings).
I’m pretty confident that my thermapen is accurate; it matches the thermometer on my blichmann kettle. I’m also pretty confident that my volume readings are fairly accurate; I’m measuring them also using the blichmann kettle as well as a fermenter I calibrated by hand, myself.
Thanks for posting the details. I included the 0.5 gal of 190°F water in the calculation since this was added before runoff. This was a total of 19 quarts strike water (4.75 gal) since they were down adjusted by about 97% to account for their temperature at measure. Assuming ‘standard’ yield for those malts (homebrew wiki malts chart), the weighted average as-is grist extract is 78.3%. The total ‘lab’ extract that you would expect from this batch is grist_mass * grist_extract = 5.34kg*.783 = 4.18 kg. Therefore, the predicted max mash gravity, m_sugar/(m_sugar+m_water) is 4.18kg / (4.18 kg + 17.96 kg (mass of water, same as volume in L)) = 18.9°P.
You measured around 16°P, which is 85% of the predicted maximum. I have similar issues in my own brewing (~90% conversion), the mashout makes the problem go away. The pH is slightly on the low side, you might bump that by .1 or .2 units as well, although I don’t think this is strictly necessary. This could just be a function of mill gap too, but if you are willing to experiment I would try the mashout and pH bump first before changing the mill gap and see what effect that has.
On to the preboil, you measured a surprisingly large volume for the amount of water used. If the absorbtion was in the normal range of 0.5 qt/lb, you should have only collected 6.68 gal, but you collected 6.96 gal (temp corrected), so I think there is at least a 1 qt error in the measurement (could be smaller errors in strike, sparge, and preboil volume that add up). I only say that because I’ve never seen a legitimate case where the apparent grain absorbtion was less than 0.5 qt/lb with regular gravity drain.
Predicting the total efficiency of a batch with a conversion efficiency less than 100% is not fully understood by me. We have to know the contributed volume of the unconverted starch that is dissolved in the wort. Kai’s spreadsheet ignores this and only calculates the volume contributed by the extract, but then this predicts an efficiency lower than what you measured. I’ll have to talk with him and see if I can come to a better understanding. Anyway, IME, unless you see standing water in the MT after you have finished runoff, you won’t be losing any efficiency there. Are you letting the first runnings go until the flow slows down to a trickle before adding sparge water?
You collected a total of 3.2-3.27 kg of extract, out of a total predicted of 4.18kg, for an efficiency of 76-78%. This predicted efficiency with 100% conversion is 85%, and I think this is all due to the missing sugar from conversion.
That was a good, detailed write-up of your last session; exactly the sort of info that will allow people to figure out what is going on for you. There were only two details that I would have wanted to see that were missing:
Now you should see the value of the Mash Gravity reading. Basically, you can expect ~85% maximum efficiency from a typical single batch sparge on an average gravity beer. If you are getting 10-15% low conversion, then you can only expect 70-75%. Less if you have a lot of dead volume in your tun.
Nyakavt gives good advice on the mash temperature bump. I was seeing occasional instances of less than 90% conversion, especially with 148°F mashes, and it that was solved by adding a step to an alpha-amylase rest. Essentially, I mash at whatever temp I would use for my single-infusion, but then add some hot water into the tun to bring it up to 158-162°F for the last 20 minutes of the mash.
[quote=“rebuiltcellars”]That was a good, detailed write-up of your last session; exactly the sort of info that will allow people to figure out what is going on for you. There were only two details that I would have wanted to see that were missing:
I didn’t take a reading for #2. As for #1, there wasn’t any wort collected prior to any water addition. I added sparge water to the tun prior to draining in order to collect two equal volumes.
[quote=“nyakavt”]…
You measured around 16°P, which is 85% of the predicted maximum. I have similar issues in my own brewing (~90% conversion), the mashout makes the problem go away. The pH is slightly on the low side, you might bump that by .1 or .2 units as well, although I don’t think this is strictly necessary. This could just be a function of mill gap too, but if you are willing to experiment I would try the mashout and pH bump first before changing the mill gap and see what effect that has.
On to the preboil, you measured a surprisingly large volume for the amount of water used… so I think there is at least a 1 qt error in the measurement (could be smaller errors in strike, sparge, and preboil volume that add up). I only say that because I’ve never seen a legitimate case where the apparent grain absorbtion was less than 0.5 qt/lb with regular gravity drain.
…
Are you letting the first runnings go until the flow slows down to a trickle before adding sparge water?
…[/quote]
I’ll definitely try raising the pH 0.2 units for my next beer, but as for the mash out, how are you mashing out with a batch sparge? (I’ve got a cooler and) I’m not sure I understand how to do both…
I’m not sure where/why a quarter gallon of extra water came from. I’ll keep an eye on it.
As to your question, “Are you letting the first runnings go until the flow slows down to a trickle before adding sparge water?”, as in my answer to rebuiltcellars, I add a small quantity of (sparge) water to the mash prior to draining anything, in order to collect two equal volumes. Are (either of) you suggesting I should try for a different method?
That doesn’t matter, as long as you mix the mash well before taking the sample for gravity and calculate based on the full volume.
The pseudo-mashout or step can be done in a cooler with an infusion, such as your addition to bring it to equal volumes. It doesn’t matter if you hit mashout temperatures, 158-162°F will be as good or maybe even better for your goal of improving conversion efficiency.
^^^ what he said. I pump the mash water through a coil in the HLT to heat it up. You could also do a small decoction, bringing 1 or 2 gallons of the mash then adding it back. I used to do it this way but got tired of cleaning grain out of the boil kettle 
OK, then did you actually collect equal volumes as you calculated you would or was it unequal when it drained?
I’ve found that I consistantly get 3x as much sugar out of the first runnings as the second if they are of equal volume. If you are getting numbers significantly different than that, there is a big clue to what is going wrong.
Silentknyght
I may be a new guy here but I think I see your problem. You are supposed to drain off the 1st load of water that you placed in your mashtun before you add the second load. Call thoese loads by whatever name (the 1st is your strike water and the second is your sparge water). The two volumens of water should NEVER be in your mashtun at the same time. The two equal volumns relates to the following. If you take the first run off and put it in one kettle and then take the 2nd run off and put it in another kettle then the two kettles should hold identical or close to it volumns. This is actually how I do it as all my preboil will not fit into one of my kettles (in lust of Keggles!!).
Barry
[quote=“Vulkin’”]Silentknyght
I may be a new guy here but I think I see your problem. You are supposed to drain off the 1st load of water that you placed in your mashtun before you add the second load… If you take the first run off and put it in one kettle and then take the 2nd run off and put it in another kettle then the two kettles should hold identical or close to it volumns.
[/quote]
This is correct for my operation. Should my strike water, when drained, not equal my second sparge for a desired preboil volume, a small first sparge amount is added to the mashtun prior to draining. This allows the first volume to equal the second.
Having a second addition to your mash prior to your first runnoff is useful if you want to do a step mash, which can raise your efficiency. If you aren’t doing a step, it’s probably more beneficial to efficiency to include that volume throughout the mash, as a thinner mash will tend to convert more completely.
[quote]don’t rely on volume measurements on the side of brewing buckets, and so on.[/quote]Is a liquid measuring cup good for accurately determining volume?
These aren’t all that accurate either, the lines are just silkscreened on and they really don’t have precision measuring in mind. Plus since the one most people have only have a 2 cup capacity, you can get a big stackup of error if you fill up to 7 or 8 gallons. 4 or 8 cup models would be better if you have them. It’s better still to use a graduated cylinder, or do it by weight with a digital scale.
My kettle has a rounded bottom then straight sides after the first gallon, so I used weight to get the irregular volume calibrated on the dip stick then used a tape measure once the sides straightened out. If you can measure to within 1/8" accurately, that’s .3 qt of error on a 14" pot. Always measuring from the end of the dip stick eliminates the stackup of error that you would get with a measuring cup type calibration.
