How fine is too fine?

[MMBB]

So for my second foray into all grain brewing I decided to re-brew centennial blonde due to bad efficiency and low alcohol content on my first try. After two weeks of fermenting the batch previously brewed is at 2.7% ABV. The OG was 1.033 and the FG is 1.014 (both readings temperature adjusted).

I went to a different LHBS that is a little closer to me where they let you measure and crush your own grains. Remembering that I read on here that most places crush, and by default I'd think set their customer use mill, for a 70% efficiency. I ran the grain through the mill twice to get a finer crush hoping to get a few extra points of efficiency.

I screwed up and didn't let my sample cool before taking a pre-boil gravity with my refractometer. So, if the sample cooled down to room temp (70) before I took the gravity, which I doubt, I have about 76% efficiency based on a pre-boil gravity of (temp adjusted) 1.034. If I guess and say it was about 100 degrees it will be 1.039 with an efficiency of 88%. Either one is acceptable to me really. Next time I'll let the sample cool before taking a reading.

My main question is if I got too fine of a crush by going through the mill twice. My efficiency went up for sure but I was also more accurate with my mash and sparge temps. However, when the mash tun was emptied the grains had formed a "cake" that had shrunk as it drained and pulled away from the walls of my mash tun. There was even a small amount of liquid on top of the cake that wasn't filtering through. The last time I brewed that didn't happen.

 

[Lucky_Chicken]

Too fine a crush is not a problem unless you are shreading your husks. Ideally you want to seperate the husks and turn the rest into flour.

 

[MMBB]

Thats kinda what I thought. I didn't know if perhaps by the grain pulling away from the sides of the tun it was bypassing the "long way" through the grain bed and going right to the screen.

I also forgot to mention that I am batch sparging.

I have alson noticed on my last two brews I have almost zero trub at the bottom of my keggle. I have been using the paint strainer bag hop bag device and full leaf hops. One batch I used irish moss at the end of the boil and the other I didn't. Is this normal when using a hop bag?

 

[Lucky_Chicken]

I havent used a hop bag so I couldnt tell you on that but I would expect a lot less.