[a witty man]

I've been trying to figure this one out. On most amber and dark beers I have my recipes dialed in at 72% efficiency, and can nail the numbers (calculated from Beersmith and Bru'n Water). When I brew paler beers, however, my efficiency drops by about 10 points.

Here's the latest grain bill:
6 gal batch; 7.81 gallon boil

10 lbs Maris Otter
5 lbs Wheat Malt
1 lb. Crystal 20

Anticipated pre-boil grav: 1.060
Actual pre-boil grav: 1.048

I got a water report in the spring of 2013, and I've been using Bru'n Water to calculate my water additions. On this one I used the "Yellow Bitter" as a guide. Here are the overall numbers I got after doing additions of Gypsum, Epsom Salt, and Lactic Acid to both the mash and sparge water:

59 Ca
30 Mg
33 Na
134 Sulfate
61 Chloride
-9 BiCarbonate
RA (according to Bru'n water) = -67

I checked my pH using colorphast strips throughout the mash, and it was a steady 5.3.

So, I'm stumped. I mill my own grain, so LHBS is not a factor. Admittedly, I am trying to figure out this water stuff on my own, referencing some books (including water by Palmer/Kaminski), so I have a feeling it has to do with that.

Any insight as to why I may be getting low efficiency on pale beers only would be appreciated! Thanks all.

[dmtaylor]

Wheat malt kernels are slightly smaller than barley kernels.  You probably just need to tighten your mill gap slightly, then watch your efficiency on ALL of your beers shoot up by 10 points overnight.

[mabrungard]

I have long encountered an efficiency drop when using wheat.  I'm not sure why that occurs, but I plan for it in my recipes using high percentage of wheat. 

Regarding your pH reading, is that a corrected reading from the strip?  They report about 0.2 to 0.3 units lower than actual and that is confirmed by the manufacturer.  So if you haven't corrected the reading, your pH could be 5.5 to 5.6.  That is a bit high for a pale beer. 

[jeffy]

I also get less efficiency with wheat, especially with raw wheat, but I notice you used wheat malt.  My efficiency gets better using flaked wheat or even torrified wheat.

[duboman]

Wheat malt kernels are slightly smaller than barley kernels.  You probably just need to tighten your mill gap slightly, then watch your efficiency on ALL of your beers shoot up by 10 points overnight.

This was my first thought as well. I know that I used to experience this early on. I now get my wheat separate from other grains and mill them separately at a tighter gap and it solved my problem, give it a try!

[a witty man]

Great feedback. The light beers I've been brewing all have wheat in them, so I will certainly check the crush out next time. It's easy enough to keep it separate and run it through the mill again.

Also, it sounds like the pH may be high - I have been trusting the ColorPHast strips to the number. It may be time to invest in a pH meter, and to start cutting my water with some RO for pale beers.

[porterpounder]

I get the wheat malt efficiency decrease, but have you also checked the pH of your sparge water? Treating the mash to get to a good pH is one thing, but I noticed a significant improvement in my pale beer efficiency when I started acidifying my mash water to about 5.4-5.5. My untreated sparge water usually runs about 8.0. Just covering all the bases.

[dmtaylor]

Good point, porterpounder.  pH could also be part of this... although I think the reason I didn't say it before is that the OP stated his mash pH was a steady 5.3, which is right on target.  So unless there is something screwing up the pH readings, it's more likely to be a crush issue than pH.

[porterpounder]

Agreed. Also a good point.