Low efficiency with Briess 60L

[Todes]

Hello I´ve been brewing for a while, and since last year I was getting consistently good results in efficiency. But I keep getting low conversion rate when I use Briess 60L. The first time I used it was in a Irish Red Ale, I was expecting about 1.045 - 1.050 OG and got about 1.036. Some time later I brewed with the same recipe but different method, this time I crushed my grain and did some improvementes but I got almost the same, 1.037. After that I´ve been brewing blonde ale and ipa, and got good results. Last month I brewed a Blonde ale and a scottish export on the same day, but this time I used Weyerman malt and got results good as expected got 1.056 OG. This week I brewed first an Ambar Ale in wich I used Briess 60L and 20L and was expecting 1.051 OG and got about 1.046. On the same day I brewed another blonde Ale and got the OG I was expecting, so I don´t think the milling is the problem. What do you think about this?

 

[chickypad]

Are you talking about crystal 60 malt? That should only be a very small percentage of the recipe, and I wouldn't expect it to drop the gravity of the whole batch by over 10 pts. Maybe it's something else like your pH is off with your darker beers, assuming everything else in your process is the same batch to batch. What was the entire recipe that gave you the low OG? Do you measure or do anything to predict your pH?

 

[Smellyglove]

Are the numbers you use to calculate the extract potential from the different grains correct? Although the lacking points are probably something else than just the extract potential from the grains.

 

[Todes]

i think you are right, i didn´t check the ph the time i brewed the amber ale and i did it with the scottish export