Low OG

Make sure your grain is properly crushed
If possible, make sure your pH is in the proper range during the mash
Take the following measurements
- total grain weight
- strike water volume / temperature
- mash temperature/ length
- volume of first runnings collected in boil kettle
- sparge water volume / temperature
- volume of second runnings collected in boil kettle
- preboil volume (combo of 1st and 2nd runnings collected volume)
- preboil gravity
- boil length
- post boil volume (as soon as the flame is turned off)
- post boil gravity
- batch size (volume that makes it into the fermenter)

With those measurements, you should be able (and we can help you) to generate all of the system numbers you need to dial in your system profile in your brewing software

QUESTION: What temperature was your wort when you took your pre boil and post boil gravity readings with your hydrometer? Did you correct for that?

 

That's not quite enough information.

What was the recipe?
What was your mash pH, and how did you determine it?
What were your pre and post-boil volumes?
How did you conduct the sparge?
How and when did you take your measurements?
How was the crush on the grain?

 

Please post your recipe and describe your equipment and mashing / sparge method.
in any case use some brewing software, it will give you guide line o where you are.

 

5.2 powder is basically bollocks, and you probably had a lot of wheat in there. Wheat will raise the pH of the mash, considerably. That could have been a considerable contributing factor.

 

Did you calibrate your thermometer?

 

OK I ran your numbers through beersmith 2.0 and came up with the following observations:

your mash extraction efficiency was at around 39.4%
your batch efficiency was at around 26%

Again, when you measured your pre boil and post boil gravity with your hydrometer, what temperature was the wort? Did you get the 1.010 and 1.021 measurements by measuring wort that was at 60F or was it hotter than that at the time of the measurement?

Next issues that would lower your efficiencies is that you said you collected 0.75 gallons of 1st runnings (original strike water 1 gallon) which sounds correct since you had 2.1 pounds of grain which should absorb roughly 0.125 gallons per pound of wort. However, if you sparged with 2 gallons, you should have been able to collect 2 gallons of 2nd runnings. Instead, you report that you only collected 1.25 gallons of 2nd runnings. That is a big loss of sugar and volume right there. Either your kettle has a very large (proportionally) dead space preventing you from capturing all of your runnings (it doesn't since you had 0 dead space as proven by your 1st runnings collection) or you did a poor job lautering on your 2nd runnings. Why did you stop collecting your second runnings when your preboil volume reached 2 gallons total? is that all of the room you had in your boil kettle? If so, you sparged with too much water. You should have only sparged with 1.25 gallons, not 2 gallons in that case.

Hypothetically speaking, if you would have collected all of your second runnings you would have had 2.75 gallons preboil at roughly 1.012 for a mash efficiency of 41% and a total batch efficiency of 26% according to beersmith.

Hypothetically speaking, if you would have collected 2.75 gallons preboil @ 1.022 SG (rather than the 1.010 SG you claimed you hit with 2 gallons preboil), that would have been a 74.5% mash extraction (which is about normal).

Hypothetically speaking, 2 gallons preboil @ 1.030 SG would have been about 74% mash extraction (which is still about normal).

The next thing I notice is that you claimed to boil down your 2 gallons preboil to 1.25 gallons in 75 minutes. That means you evaporated 37.5% of your batch in 75 minutes. That does not sound plausible. It should have been closer to 10% or 0.2 gallons.

You also mention that your 1.25 gallons post boil volume = 1 gallon into the fermentor. That is plausible. That is about 0.05 gallons for cooling expansion loss and about 0.20 gallons for trub and transfer loss (assuming you left some break material and proteins in your boil kettle rather than transferring everything to your fermentor).

 

Love all the mathwork, but I have to disagree on this one point... His reported boil-off was only 0.6 gallons per hour, which doesn't sound implausible to me. FWIW, I never calculate boil-off as a percentage. Given the same system configuration, putting only 2 gallons in a kettle won't significantly slow down the gallons/hour boiled away as compared to, say, 5 gallons in the same kettle. (At least not until you're into syrupy range.)

 

Fair enough thanks. Not knowing his kettle size, would you suggest that is due to a proportional increase in surface area for the smaller batch or something?

 

Sort of. It's really due to the boil-off (in gallons/hour, not percent per hour) being relatively constant for any given surfaca area, boil strength, humidity, pressure, etc. i.e. the process doesn't really care how much water is deeper down in the kettle. But yes, if you think in terms of percent per hour, the percent per hour for the smaller batch would be higher, because the ratio of that surface area to the volume would be higher than it would be with a bigger volume.

 

Easiest way to think about it is this..

Mash with your normal volumes.

Collect EVERYTHING from your 1st runnings.

From there, figure out, via kettle marking, dip stick, sight glass, whatever, what you collected. If you got 1 gallon, and need 2, then sparge with only 1 gallon.

Collect the whole 2nd runnings. That way you don't leave any water behind laden with sugars from the malt. If you end up needing to sparge more, adjust your boil length, assuming you know what your boil off rate is.

 

Even if you nail down your sparge, you still need to get control of your pH. Adding 5.2 stabilizer isn't a good way to do this.

Your mash efficiency will drop off considerably if you are below 5.2 or above 5.7:

http://braukaiser.com/wiki/index.ph...ity_and_efficiency_in_single_infusion_mashing

Efficiency aside, pH is important for other reasons, and is something you absolutely need to pay attention to.