Hi!
I noticed that I don't get anywhere close to the gravity Brewfather estimates for a given recipe. Latest example is a SMASH IPA with a good 5 kg of pilsner malt that, which on my BrewZilla Gen 4 should have landed me somewhere around 1.054 pre boil. Everything went according to the recipe: 71 °C strike water, 64 °C mash for one hour (even a tad longer than that due to being interrupted by having kids), nice recirculation all along, no visible dough nests. What I got though was a pre boil gravity of 1.037 (forgot to test for starch being still present with iodine though).
This is only my fourth brew on the system, the first I forgot to measure and two were rather experimental, but I am still noticing a pattern here in that my efficiency is rather consistently sub par. I now wonder where to find room for improvement. For me, there's no need to squeeze every last bit of sugar out of my grains, yet at a mash efficiency of only 54% where in theory I might even get 80% does not only strike me as unnecessary wasteful, this way I don't know if I could even make anything bigger than an IPA at all without stretching the limits of my system.
My grain milling is one of the things that I suspect might contribute. So much so that I already wish I hadn't bought a three roller mill but one that I can adjust with simple advice from the internet, it seems everything in this field is geared towards two roller mills.
Also I started thinking about pH. Until now I never tampered with it, does it really have the potential to make such a huge difference?
All other suggestions are welcome as well. Cheers!
71 °C is the temperature that will drop down to 67 when adding the room temperature grains, yes. The grains are also fresh, I bought them only a couple of months ago and stored them in air tight buckets with click- or screw on-lids ever since.
I know about the purpose of a step mash and my last two brew days involved them, yet without benefit. What I picked though up is that given today's grains, starting the mash as low as 50 might even be detrimental to the head retention as the proteases might eat away more protein than required. But on this, I'm only reciting theory learned elsewhere and can't speak from experience.
I just read comments here for the last few days. But what I would try is start lower, the 78°C temperature denaturates alpha and beta amylase, you are well under that temperature but guy from brewing institute here suggested to me few years ago that 64°C is optimal for malts nowadays (in home setups).
Other than that as suggested in other comments check flow and your malt crushing.
Iodine test may point you in right direction, it may occur in sparge - negative starch test, or before that - positive starch test before sparge.