Comment on Potential reasons for undershooting gravity
solidgrue@lemmy.world 3 months ago
Low brewhouse efficiency can be a bear to troubleshoot. Usually they’re procedural problems. Tweaking the chemistry gets you a few points, if you’re off 10% or more off your target efficiency, it’s usually something else.
One of the things that can hit your efficiency numbers is a stuck sparge, or channeling in the mash tun. Sparge water finds the path of least resistance to the spigot, so if the grain bed is uneven, the sparge water will bypass the denser inclusions and leave sugar on the table, sort of like a stream cutting a channel in the mud.
Your grind might be contributing to that situation if it’s too fine, and you have too much flour in the mix. You need to stir it really well after strike, and then let it settle. If you can adjust anything on your mill to reduce flour that will certainly help. Otherwise adding rice hulls to the mash help to even out the consistency of the grain bed.
One trick I used to use would be to give everything one last stir at the end of the mash, and then pull a couple liters of wort to gently pour back on top. Is repeat the process into the wort ran clear. This would help to even the grain bed and then help it settle.
Other contributing factors could be how fast you sparge. Too fast and you’re not going to capture all the sugars. Slower is generally better, since it gives the fresh water time to dissolve any extra sugars left in the grain. It also helps to reduce channeling.
My typical efficiency was 75%, maybe 80% on a very good day, but I tried to remind myself that chasing efficiency only got you frustrated.
Hope any of this helps!
Aarkon@discuss.tchncs.de 3 months ago
I absolutely agree that going for perfection is a recipe for unhappiness. It’s only that I’d like to remotely get into the ball park of a recipe. At the moment, I’m so far off that I wouldn’t even dare to try Belgian beers, strong stouts/porters or anything like that, just because I wouldn’t know how to fit enough grain in my mash tun should I try to correct for the low efficiency.
That said: As I also like coffee, I’m aware of how challenging works. I believe I stirred seriously, but you never know. Other than that my recirculation was not continuous, instead I set the pump to 60% - which turns it off 40% of the time, allowing for some backwards flow to happen. This is often enough to free the pump if it’s blocked, so I hoped it would help agitate the grain bed in a way that prevents channels from forming. Again, you never know.
If anybody reading this who also uses an AIO-system like BrewZilla, Grainfather and such and might care to share photos of their grain crush, that might also help me.
solidgrue@lemmy.world 3 months ago
I’ve never heard of back flow during a sparge before, but it’s an interesting idea. Is that a common practice these days? I quit brewing maybe 10 years ago, and I was doing 20L batches with gravity feed. It was when the AIO systems were starting to become affordable.
Aarkon@discuss.tchncs.de 3 months ago
Sorry if I expressed myself not clearly - when my pump is turned off, wort is flowing down the recirculation pipe due to gravity instead of up. It’s not a big amount of liquid going into the other direction, just enough to free up a clogged pump often enough. Also, this happens during the mash, not the sparge.