Low OG on a random batch of left overs

[jdemars]

Sooooo,

8 lb pale 2-row
0.5 lb vienna
0.5 lb crystal 10L
Crush 0.25 mm

20 min rest at 131°F
100 min rest at 150°F
mash with 5.2 stabilizer 4 gal
60 min sparge 170°F 2 gal

0.5 oz cascade at 60 min
0.5 oz centennial 15 min

Brewing with a robobrew.

Expected OG 1.048, at 70% efficiency, actual OG was 1.025.

Ideas? I figured with that long of a mash I would have gotten every last bit of sugar out of there. I'm using a refractometer to get the gravity.

 

[RM-MN]

Who crushed the grain? Since in most cases the crush of the grain determines the mash efficiency the crush is the most important part of your efficiency.

 

[jdemars]

I did. Hit of on last batch same crush.

 

[Soulshine2]

1-What style beer are you aiming for?
2-how many gallons is the expected finished batch ?
3-I see 9 lbs of grain and 6 gallons of water... your grain/water looks a bit thin to me if this is a 5 gallon batch, If this was me,I'd add another 2 lbs of grist.
4-how long was your mash ? I mash at 152-154 for 60 minutes, no less...I may get busy and its 5 more minutes but the saccharification is done long before then anyway. Once, I mashed at 163, I overheated my strike water and after adding it to the tun, i expected it to go down after adding the grain but I found out my digital thermometer in the tun wasn't reading correctly...waaaay off. Beer turned out ok. but, I now only use a glass thermometer for this reason.
5-in what order were the rests?
6-why was your sparge temp so hot, 170*F?
7-How long was your boil? Possibly , you didn't boil enough off water.
8-what was your pre-boil volume vs your post-boil volume? see #7.
and
9- do you check gravity pre-boil and post-boil?
10a-do you own/use a (calibrated)hydrometer at all?
10b-do you own/use a calibrated (glass/floating)thermometer?
11- have you always used a Robobrew or did you brew "manually" prior to this?

Just making sure I'm reading your process correctly. Don't take it personally,I'm not saying yours or my method is right or wrong. I brew 5 and 6 gallon batches because thats what most HB recipes are designed for. I like to brew more hands-on and simply than trust turn key electronics in shiny expensive gadgets. Batteries/power fail, probes don't read correctly , hoses leak/kink and pumps can quit,clog.

 

[bracconiere]

does sound like a loose mash. did you change that for this one from the last? and if you mashed with 4 gal, and only sparged with 2...did you boil it at all?

even if the grain didn't absorb water from the mash, it would only be 6 gals? i've always pretty much sparged with the expected final volume, and reduce...but never used a robobrew.

edit: i just looked in beersmith, and it calculates that, that much grain wouold absorb 1.08 gals. so you would have started with 5 gals?

 

[doug293cz]

Your pre-boil SG should have been about 1.052 with that grain bill, the water volumes you used, and an assumed 95% conversion efficiency. So, your conversion efficiency had to have been in the dumpster. How old was the pale malt? Perhaps it's enzymes had faded away.

Did you really crush at 0.25 mm (0.010")? That's extremely fine, so crush would not be an issue.

Brew on

 

[jdemars]

I plugged all of my numbers into brewers friend and that was what I was expecting to get close to, with that being said . . .
1-What style beer are you aiming for? No specific style, playing around with ingredients. Used an english ale yeast with lighter grains.

2-how many gallons is the expected finished batch ? 5 gallons

3-I see 9 lbs of grain and 6 gallons of water... your grain/water looks a bit thin to me if this is a 5 gallon batch, If this was me,I'd add another 2 lbs of grist.
The mash was with 4 gallons, the boil started with 6 gallons. Is grist crushed grain?

4-how long was your mash ? 2 hours . . .

5-in what order were the rests? listed originally, but 1st, 20 min rest at 131°F and 2nd, 100 min rest at 150°F

6-why was your sparge temp so hot, 170*F? I thought that it needed to fly sparge at my mashout temp?

7-How long was your boil? an hour, hit the 5 gal in the fermenter as calculated by brewersfriend

8-what was your pre-boil volume vs your post-boil volume? 6 then 5 respectively.

9- do you check gravity pre-boil and post-boil? yes, little to no change, 1.024 to 1.025 respectively. This was with a refractometer that I have previously compared to calibrated hydrometer readings and found them to be within a point of each other.

10a-do you own/use a (calibrated)hydrometer at all? Yes but did not for this batch.

10b-do you own/use a calibrated (glass/floating)thermometer? no, I always seem to burn my fingers.

11- have you always used a Robobrew or did you brew "manually" prior to this? Brewed manually and much prefer it but the guy I'm brewing with insists that we use the robobrew because it has been -15 out the last few brew days.

With that being said we have had good batches with the robobrew and manually, again I prefer manually but the weather outside is a huge deterrent.

Thanks for the help all, I have been reading a bunch on here! Cheers

 

[bracconiere]

i mash with 7 gals for 20lb...sparge with 10 gals, and only get 13.5-14

i guess i'll have to look at the robobrew process, not sure how you could mash in 4 gal water sparge with only 2, and still boil for an hour and get 5 gals?

i'd say it'd be a lot better to mash in 2 gals and sparge with 5 for a 5 gal batch? did you accidentally get those volumes backwards?

 

[Dgallo]

i'd say it'd be a lot better to mash in 2 gals and sparge with 5 for a 5 gal batch? did you accidentally get those volumes backwards?

Mashing with 2 gallons of water and 9 lbs of grain and sparging with 5 galw would be terrible for efficiency. Having more water in the mash would actually increase your mash conversion and then sparging with the correct amount would benefit your efficiency for doing a thinner mash. The ideal mash should have been closer to 3 gallons

There is certainly something incorrect with your temps(thermometer related because your temps you stated are fine) or your crush. Your pre-boil should of been around a 1.032-1.034 so that shows you there was something wrong. So that’s what you need to figure out.

 

[IslandLizard]

Just a few observations:
Is this the first time using the Robobrew?
Did you mean 0.025" perhaps? 0.25mm is 0.01" and makes flour!
If 0.025" the crush may be too fine for the Robobrew? The water can't permeate the grist very well, it plugs up?
Did you stir the mash manually at dough-in and then let the Robobrew take care of all the recirculation after that?
Mash temp is important, although raising it from 120 to 150 slowly alone should almost convert it, then the extra 100 minutes at 150 converts whatever is left... unless:

• The mash was overheated during the step up
• The actual mash temp was much higher (or lower) than the target
• There was lots of channeling along the sides and not much flow through the middle
• What did the grist look like when you dumped it out? Dryish in the middle perhaps?
• Your refractometer is broken. When you see an unexpectedly low reading why not double check with a different instrument, such as a hydrometer, to be sure?

You don't need pH 5.2. It's snake oil, doesn't do a thing for your mash and even fights the proper pH, unless you use RO or distilled water. In which case there are much better ways to control your mash pH and get the correct mineral balance.

 

[bracconiere]

Mashing with 2 gallons of water and 9 lbs of grain and sparging with 5 galw would be terrible for efficiency. Having more water in the mash would actually increase your mash conversion and then sparging with the correct amount would benefit your efficiency for doing a thinner mash. The ideal mash should have been closer to 3 gallons.

your right, 3 gal would be 1.3 qt/lb.....i just remember when i was still brewing 5 gal batches i sparged with 5gals of water, and got like 6 give or take in to the boil kettle....now i use 21lbs with 7 gal, and sparge with 10....and get 13 or so...

i'm curious what his pre-boil volume was? did you top up the boil kettle with water pre-boil?

just wondering, because i am right that grain absorbs some of the water? or no?

edit: not trying to argue just working on a puzzle....BeerSmith tells me 9 lbs of malt will absorb ~1 gal of water, he used 6 total...and said he boiled for 60 min..and got his 5 gal target....

 

[doug293cz]

As previously noted, your volume numbers don't add up. 4 gal strike and 2 gallon sparge with 9 lb of grain would only net about 5 gal pre-boil. If your 4 gal strike and 6 gal pre-boil are correct, then sparge would have to have been about 3 gal. First and second runnings would have been equal volume - ~3 gal each. Kai Troester has shown that equal runnings volume is optimal for lauter efficiency when batch sparging. Kai has also shown that thinner mashes convert faster than thicker mashes. So, might as well forget all the nonsense about 1.25 qt/lb being best for mashing (unless you are fly sparging, where the lauter kinetics are completely different.)

Brew on

 

[bracconiere]

(unless you are fly sparging, where the lauter kinetics are completely different.)

Brew on

I fly sparge, and i believe op said this was also...

and back at ya

edit: but that's my puzzle....he says he boiled for 60 min AND GOT 5 gals at the end? only way i can see that is if he topped the boil kettle up with plain water before the boil...

 

[jdemars]

So . . . turns out the robobrew is essentially a BIAB situation and I was recirculating the "first runnings" through the bag to try and clarify the wort. Then I was also pouring 170° water over the top thinking I was rinsing the grain.

After reading more about the BIAB process it seems like I would need to modify the recipe and add more water.

Also, there are no units on my mill but it does read 0.025 not 0.25 as I stated. I imagine that this number is in inches.

The date on the grain was good still. This is our second time milling our own grain, the first time we followed the same steps as I have been mentioning and got just about spot on results. IDK, it's another batch that will probably be drinkable, and I'm ok with that.

Thanks again.

 

[kh54s10]

The one thing I noted was 1.024 preboil and 1.025 post boil. This seems unlikely and that a measurement error occurred on one of these. 6 gallons boiled down to 5. That sounds probable if the boil is minimal.

My propane boils vigorously at the lowest setting that keeps the flame lit. I boil off 2 gallons per hour.

 

[RM-MN]

Also, there are no units on my mill but it does read 0.025 not 0.25 as I stated. I imagine that this number is in inches.

Most likely the setting of .025 is inches but that may not be accurate. Best is to get a set of feeler gauges and verify that the setting matches reality. Barring the feeler gauges, a credit card will be an acceptable substitute.

 

[IslandLizard]

Most likely the setting of .025 is inches but that may not be accurate. Best is to get a set of feeler gauges and verify that the setting matches reality. Barring the feeler gauges, a credit card will be an acceptable substitute.

This^

A normal credit card is about 0.034" thick, that may be a bit too coarse for regular BIAB, but may well be about the minimum width for recirculation mashes like in your Robobrew or a Grainfather, to prevent it from plugging up.

2 of our club members use a Grainfather and each one has been Homebrewer of the year the past 2 years. Their beer is great! They buy their grain at our local homebrew shop and mill it there. That mill is as coarse as can be, a gap so wide that half the wheat kernels pass through whole, uncrushed! But the machine's recirculation helps with extraction efficiency of everything that does get crushed. Aside from crushing wheat separately at a narrower gap setting, a finer crush overall may not be advantageous with those systems.

As I said before, 0.025" is most likely too narrow for your system. Start with a wider gap, [Edit] 0.040", and if you want, go narrower with each next brew until you don't see any more improvements or start getting problems. Then back up a notch. That would be your equipment's optimal setting.

Small kernels like wheat and rye will still benefit from a separate crush on a bit narrower gap. I mill my wheat and rye on 0.028" everything else at 0.034. But I use a converted cooler as a mash tun, not a recirculating brewing machine.

 

[kh54s10]

Edit needed for post #17. I don't think a 1" and .040 gap will crush any grain. Maybe pecans or such. But, we can look past the typo and see that the advice is sound.

Feeler gauges are definitely advised. My Cereal Crusher is set to about.030 and a credit card will not pass between the rollers. Now I need to visit an auto parts store. Also, by eye my rollers are parallel but the scale on each side is different. 2 batches on my new mill, the results are about the same as my old Corona, so some fine tuning seems to be needed.

 

[IslandLizard]

Edit needed for post #17. I don't think a 1" and .040 gap will crush any grain. Maybe pecans or such. But, we can look past the typo and see that the advice is sound.

Thank you for pointing out the error, that was indeed a typo. Should have been 0.040" gap. Fixed!

Feeler gauges are definitely advised. My Cereal Crusher is set to about.030 and a credit card will not pass between the rollers. Now I need to visit an auto parts store. Also, by eye my rollers are parallel but the scale on each side is different. 2 batches on my new mill, the results are about the same as my old Corona, so some fine tuning seems to be needed.

I really like using the credit cards for that. I guess one can be sanded down a little on one side to make a new gauge.

On your new mill make sure to adjust the gap so the slave roller approaches the driven one from the underneath. Do that on both sides. That way the roller will be pressed into the lock down bolts during the crush, and hold the correct gap setting, rather than being allowed to wander away.