Consistently low OG

[mlevings12]

Okay everyone, Need a little help here.

I consistently have one of two problems:

1.) I hit my OG, but my water volume is significantly low (like at least a gallon short).

2.) My water volume is dead on, but my OG is too low.

Latest example is a Russian Imperial Stout. Hit my expected volume, but my pre-boil gravity was 1.055 (instead of the projected 1.072). I used 18lbs of 2-Row (21.25 lbs of grain total). Mash was held steady at 150F for 60 minutes. I have checked both my thermometer and hydrometer for accuracy and there's no problem. I confirmed the hydrometer measurement using a friends refractometer.

I'm using Beersmith. This has been a consistent problem since I began using the program about a year ago.

Thanks in advance!

 

[brettg20]

Sounds like something in the settings, do you have your profile dialed in? Boil off rate?

 

[thadass]

When you enter your results into BeerSmith, what does it give you as your measures efficiency? What efficiency expectation are your recipes using? If they're not the same, you might want to adjust the efficiency expectation of your recipes to match what you're actually able to get.

Now, that's just pre-brew preparation. Without knowing what actual efficiency you're getting, it's hard to even speculate on whether you have a real problem or not. If you could, though, tell us more about your process. Cooler MLT, BIAB, milling grain at home, brew shop, or ordering milled online?

Are you using tap water or store-bought? Do any water additions? etc

 

[ScottG58]

What is the size of your mash tun? I get crappy numbers with RIS because the grain volume pushes the limits of my 10 gallon round cooler setup.

 

[acidrain]

Your projected pre-boil gravity was 1.072? You got 1.050 pre-boil (just double checking the pre-boil... sounds high)?
What was your projected OG, and what was your boil-off rate?
Like others have asked... have you entered YOUR equipment profile into beersmith with boil-off rate and efficiency?

 

[mlevings12]

Thanks everyone! I will address these questions in the most logical order, and if I miss anything, just let me know.

Brettg20 - I would say my settings are pretty dialed in. If I had to give it a number, I would say I'm 95% confident. The only thing that throws me off is the mash tun dead space. I filled my MLT with water and drained without tipping. I had a gallon of liquid remaining below the braided hose. However, when I set this parameter to 1 gallon, I had like nearly a gallon more wort than anticipated. Currently I have it set to .2 gallons. My boiloff rate is 1.2gallons per hour. I did a water test and boiled at the same intensity as my typical brew day boil.

Tadass - This is what I was thinking was the issue. Beersmith defaults to 72% Total efficiency. However I'm getting different results (typically between 55 & 66% Total efficiency). The most current numbers are as follows:

Total Efficiency - Estimated: 72.0% / Measured: 65.7%
Mash Efficiency - Estimated: 73.3% / Measured: 56.4%

I'm confused on two things here:

1.) What is the difference between these two? I've read a lot on how Beersmith misinterprets the concept of Total Efficiency, however after 6 months of reading posts, I'm more confused than before.
2.) What is the cause of the consistently lower numbers? My hydrometer and thermometers all have tested positive for accuracy.

Process is as follow: Grain crushed at the LHBS. I use a 10 gallon cooler for my MLT. I always preheat it and on occasion it will drop 3-4 degrees over the hour mash (this time it stayed consistent at 150F for the entire hour). I use a braided hose filter and I batch sparge at 168F). My water is pretty good for brewing I'm told by the friendly folks at the LHBS, so my water additions are limited to some gypsum if I'm doing an IPA, but that's about it.

ScottG58 - My MLT is a 10 gallon cooler. I get consistent(ly low) results regardless of the style, grain amount, etc.

Acidrain - Estimated preboil gravity was 1.072 (just confirmed in Beersmith). Projected OG was 1.098 (measured was 1.089). Boil off rate is 1.2gallons/hour.

Mashed 31.88 quarts @159F. At 21.25 lbs, this represents roughly 1.5 quarts / gallon. Sparged with 2.4 gallons @168. I only drained the mash tun about 2/3 of the way prior to batch sparging. I did this to ensure that there was enough liquid to mix the grains thoroughly during sparge.

Okay, I think that's it. If I missed anything, let me know. Thanks again everyone!!!

 

[mlevings12]

So I've been listening to the Beersmith podcast with John Palmer and Colin Kaminski on water. I have never been concerned with mash pH before. I wonder if my mash pH is getting too low. According to Colin, your efficiency starts to diminish as you move down in pH. Any thoughts?....

 

[acidrain]

So I've been listening to the Beersmith podcast with John Palmer and Colin Kaminski on water. I have never been concerned with mash pH before. I wonder if my mash pH is getting too low. According to Colin, your efficiency starts to diminish as you move down in pH. Any thoughts?....

True, but I've never had a problem with too low... only too high. Dark malts are more acidic, so yeah, that could be a factor.

To answer your question between mash efficiency and brewhouse efficiency... mash efficiency is a direct measurement of how well the sugars were converted. To me, this is the important measurement.
Brewhouse efficiency measures how much volume and sugar went into the fermenter. I leave trub and head space behind, so I have BH efficiency in the 65% range, but pretty good mash efficiency of between 75%-80%. I just got a new Barley crusher, so I'm hoping to get a more solid number in my mash efficiency.
Speaking of which, I suspect maybe your low mash efficiency numbers could be due to poor grain crush. Can you access the grain mill and actually measure the gap?

 

[mlevings12]

I think I can probably ask them what their mill is set to. If they're unable to tell me or unwilling to change it, do you think it would be helpful to run it through twice?

 

[acidrain]

I think I can probably ask them what their mill is set to. If they're unable to tell me or unwilling to change it, do you think it would be helpful to run it through twice?

I always do, but if it is crushed too fine, particles get stuck in my RMS.
Would be a good experiment for you to see if you get a boost in efficiency.

 

[mlevings12]

Okay. I'll try that. Thanks for the help.