Consistent low O.G.

[whoitis]

Hey all, long time lurker, first time poster. (please go easy on me)

Myself along with the help of a friend built a HERMS setup using a chugger pump, used AB keg for the MT and a large pot for the HLT. Rather than having a false bottom in the MT, we have a Mash/boil screen.

We've brewed about 6 or so recipes using this setup and based on calculations from to brewtoad and brewersfriend our O.G. is consistently lower than it should be. For example, last night we brewed a porter with a grain-bill of 12.75 lbs worth of grain (10lb 2-row, 2lb 60L, .5lb choc and 1/4 lb black patent) According to brewtoad, O.G. should have been 1.068 (at 75% efficiency). We mashed for 90 min rather than 60 at a pretty consistent 152-155. We did the longer mash to attempt to help offset the low O.G. problem that we've been having.

We batch sparged with 4.75 gal of 165 degree water and the mash contained 4 gal of water.

Based on this info, is there anything obvious that we are consistently doing wrong that is preventing our O.G. from being higher?

 

[DrWill]

Could be a few things. My first guess would be fineness of your crush. If your crush is too coarse you may not be getting enough surface area contact in 90 minutes even. The second is that IIRC you're batch sparging, and some brewers do report getting diminished efficiency with a batch sparge (others don't.)

I would try a finer crush and if that doesn't work, just throw in a few extra pounds of grain. On a homebrew scale, that's pretty cheap. The other alternative is to be prepared to bump up your gravity with extract or sugar depending on the recipe.

 

[lostcheesehead]

When I first started AG, I also had problems with my mash efficiency. You don't say how low you're undershooting your goal, but I do see a couple areas you can fiddle with. First, as DrWill says, take a look at your crush and make sure it's fine enough. Second, raise the temperature of your sparge. Most texts say that you should use 168-degree water, but in my experience I always go a little higher, sometimes up to 175.

Third, and this is where you may need to get creative, try fly sparging. I batch sparged for a while, and always with pathetic results. As soon as I started fly sparging (and doing it SLOWLY), I saw my efficiency jump to 75% right off the bat. A little more tweaking (crush, no mashout, etc.) and I hit the low 80%-range with ease. Good luck, don't worry, and just fiddle around. You'll find something that works for you.

 

[beergolf]

You did not mention how much lower your Og is. If it is only a few points, just adjuct the efficiency in your brew software.

I would rather have good consistent results than getting different results every time. I get around 72% efficiency almost every time and I am fine with that.

 

[chickypad]

Like others, I'm curious how far under you are talking. But I'll ask the obligatory measurement questions - are you measuring your final volume exactly, and are you measuring a cooled sample? Other than that I would look crush first like everyone else. I have come to believe this is the biggest single factor for me as I have 3 different systems and different sparging techniques and I get pretty much the same 77-79% efficiency on all.

 

[Yooper]

If your efficiency is lower then 75%, then just change the efficiency to the % you actually get. The number itself isn't important- what's important is consistency. If you get 68% all the time, that's far better than 65% one time and 85% the next time.

My efficiency on my first set up was 70%. On this set up, it's 75%. It's not good or bad- it just is what it is.

If it's low, as in under 65% always, then there are some things you can do to improve it and maintain consistency. But figure out what your efficiency is first, to see if it's actually low. It probably isn't, it's probably just fine.

 

[stevehardt]

As others have mentioned....

How low is your OG and efficiency?
Check your crush
Check your water volumes...are you using to much sparge water and starting with too much pre boil wort?
Be sure your hydrometer is calibrated and that your are temp correcting
Make sure your first and second runnings are well mixed before you take a reading.
As Yooper said, consistency is the name of the game, as long as your efficiency isn't horrible

Hopes this helps

 

[cluckk]

I was getting 65-68% efficiency, pretty regularly--though sometimes lower.

I did two things:
1. I bought a grinder so I could get a finer crush than the LHBS was doing.
2. Adjust mash pH using Bru'nwater to calculate. For a long time I used the pH reported on my water report to start my calculations, but I got a pH meter and take readings at several points during setup and mash-in. My water report said 8.0 pH, but I found that my filtered water from the tap was 7.3 pH. Water reports are not exact and cover a huge area that can have wide differences, so if you start monkeying with your water pH--which eventually you should--use a meter.

With these changes I have been pushing 80-84%. By the way, I batch sparge. I am considering running a batch with fly sparge to see if it makes a difference for me. Of course, I have to wait until I decide on something I want to make two identical batches of for comparison.

 

[Zoidberg]

Calibration of equipment is key, Make sure your thermometer is working correctly, boiling water should be 212F and to check low temp to make sure its consistant I crush ice in a styrofoam cup and add a little water and this should read 0F

Next check hydrometer and I double crush my grains (on LHBS machine) and I get 77-80 rather than 62-65 like I did before ON THE SAME SYSTEM

 

[scottballz]

I always like to do a double batch sparge. This seems to help a lot with efficiency, especially on higher gravity recipes, and bump up your sparge temp to 168. I think the combo of the two will get you higher efficiency. I usually hit in the mid 80's. And def check your hydrometer for calibration.
Cheers

 

[BackAlley]

What volume in the fermenter are you looking for? There's no way I'd get 1.068 with 12 3/4 lb of grain for a 6g after the boil. 1.060 maybe on a good day.

 

[eric19312]

What volume in the fermenter are you looking for? There's no way I'd get 1.068 with 12 3/4 lb of grain for a 6g after the boil. 1.060 maybe on a good day.

+1 to this

I ran the numbers through my software assuming 7 gal pre boil, 6 gal post boil, 5.5 gal transferred, 75% efficiency 1.059 OG
Total water required mash+sparge is 8.53 gal

Since you used 8.75 gal you should have collected 7.25 gal runnings
I then went back and checked...sure enough, if you collected 7.25 runnings, and boiled down to 5 gal, and somehow transferred all 5 gal, you would be at 1.070 OG with 75% eff.

So what was your pre-boil vol?
What was your post boil vol?
And how much did you transfer?

 

[chuckstout]

Being consistant is all that matters!.

 

[whoitis]

Wow! Thanks for all of the replies. I'll try to answer y'all's questions as best I can. Our OG from the Friday night brew (12.75 lbs of grain) was a disappointing 1.04. Nowhere close to where I wanted to be. (1.06+)

Most of our brews range between 1.03 and 1.04. When they should be closer to 1.055. We've only hit 1.05 once and I'm not sure what was different about that batch.

We use a barley crusher for our mill and I used my feeler tool to measure. Looks like it's right around .038".

I'll definitely experiment with a fly sparge and see if that helps. I was also considering a false-bottom for our MT to see if that makes a difference. Thoughts?

 

[whoitis]

Fermenting 5gal. Pre-boil was around 6.25 or so.

 

[eric19312]

Wow! Thanks for all of the replies. I'll try to answer y'all's questions as best I can. Our OG from the Friday night brew (12.75 lbs of grain) was a disappointing 1.04. Nowhere close to where I wanted to be. (1.06+)

Most of our brews range between 1.03 and 1.04. When they should be closer to 1.055. We've only hit 1.05 once and I'm not sure what was different about that batch.

We use a barley crusher for our mill and I used my feeler tool to measure. Looks like it's right around .038".

I'll definitely experiment with a fly sparge and see if that helps. I was also considering a false-bottom for our MT to see if that makes a difference. Thoughts?

Sounds like you are doing things right and your numbers are still off by a lot more than they should be. I wouldn't expect fly vs. batch sparge or false bottom vs. braided coil/bazooka screen to be worth more than about 5% in efficiency. Might improve clarity of pre-boil wort but these will be minor differences. I batch sparge with your set-up and routinely get 70-80% efficiency...on high side with low gravity beers, on low side with high gravity beers.

Your crush sounds fine. I use a BC too, I set it a little finer, maybe .035 using the feeler tool. I've played with conditioning wort which permits a narrower setting but didn't see obvious improvement and went back to dry crushing.

You mashed 90 min, that should provide further compensation for not having crush exactly dialed in.

Might be your lautering rate. I tend to go kind of slow. About 20 min to train my cooler for first runnings, then another 30 min to collect second runnings.

I'm still curious about the rest of the batch data. Especially Pre boil vol / Pre boil grav / post boil vol / post boil grav (although you said it was 1.04) / transfered volume ... That will help make sure we are talking about same problem.

 

[whoitis]

I'm still curious about the rest of the batch data. Especially Pre boil vol / Pre boil grav / post boil vol / post boil grav (although you said it was 1.04) / transfered volume ... That will help make sure we are talking about same problem.

Pre-boil volume was around 6.25 gal, post-boil was around 5.25. Post-boil gravity was 1.04 and I transferred 5 gal to the carboy. Unfortunately I did not take a pre-boil gravity reading. I hope this helps. Thanks again for the input!

 

[eric19312]

Pre-boil volume was around 6.25 gal, post-boil was around 5.25. Post-boil gravity was 1.04 and I transferred 5 gal to the carboy. Unfortunately I did not take a pre-boil gravity reading. I hope this helps. Thanks again for the input!

No particular order:

I checked your screen. That looks like the same one I'm using in my rectangular mash tun. I don't think you need to switch to fly sparging or invest in a false bottom to get the efficiency you are looking for.

It will probably help sort this (and future brewing mysteries) to get in habit of taking better notes during brew day. Try to record volumes and gravities as you go. Refractometer makes getting in-process gravity readings easier. Don't trust your brewing partner to take good notes, you should both take notes and compare at the end.

Reconfirm your measurements. Are your volumes from a calibrated stick or sight glass? How did you calibrate, and if using a stick how do you make sure your measurements are repeatable? Check your thermometer calibration with ice and boiling water. Check your hydrometer or refactometer calibration using distilled water at 60F. Check your scale too. Maybe you didn't really have 12.75 lbs grain.

It looks like in this last batch, assuming all your measurements were right, that you left about 1 gallon of low gravity wort in your mash tun. You mashed with 4 gallons and sparged with 4.5 gallons, should have gotten total of 7.2 gallons into your kettle but you only got 6.2. That gallon of wort you left with the grain would have been worth about 7 efficiency points. Not the 20 points you are missing but not insignificant.

Hope this is helpful.

 

[whoitis]

Hope this is helpful.

Very helpful indeed. Thanks for the reply!

We'll try again with closer attention to detail and better notes. I do believe that you might be on to something about the amount left in the MT. I'm also going to look into a refractometer too.

 

[whoitis]

Oh, and incase anyone is interested in seeing our little setup. Here's a pic.