Bear with me, this might get lengthy.
I always assumed my RIMS system gave me a pretty efficient mash, but about 5-6 months ago, I experienced a more than 10% drop in my numbers. Concerned, I started learning more about crush, and water chemistry to try to figure out the problem and eliminate variables.
This weekend I did an experiment and saw my brewhouse efficiency jump to 85% on a 1.085 IIPA, which is not a small beer.
The background:
I have a single tier, three vessel, two pump system running a direct-fire RIMS mash. It's the basic analogue brutus10, with no automation. Once I had my system dialed in and I got into a good routine, I saw efficiency hovering between 77-79%, which I feel are more than respectable numbers for regular gravity beers. Higher gravity brews obviously result in a lower efficiency simply because most people don't feel like pulling 9 gallons and boiling 3 off in a 2.5 hour boil. We take less and leave residual sugars behind.
I digress.
When mashing, I use around 1.5 quarts of water per pound of grain. I dough in, stir to distribute and remove air bubbles, and let it sit for 10 minutes before starting my RIMS pump. I stir it again at the 5 and 10 minute mark because I learned the tiny trapped air bubbles on the grains and in the water eventually gave me cavitation issues. After implementing the pre-pump stir routine, that issue vanished.
My mash tun is a Blichmann 10 with the Blichmann false bottom. I love it; it's great. I can recirculate at a fast rate and not stick the mash. Good flow.
The mash filters itself pretty fast, with the liquid running cloudy, but debris-free within a minute or so. During the mash, the cloudy liquid eventually runs clear as the starch converts to sugar.
Several months back, as I mentioned, my efficiency dropped more than 10% and I started investigating. I eventually learned my LHBS widened the gap on its mill (I grind in-store), but the investigation process taught me about water chemistry, and my beers have benefited accordingly.
That's not relevant now, just background. Here's my issue: This weekend on the IIPA I decided on a whim to give the mash a stir after about 45 minutes. The liquid was running clear, I hit and maintained my temps, and am honestly not sure what possessed me to do it. The liquid flow became starchy cloudy again (definitely not particulate matter), and it didn't clear up for another 30 minutes.
I can only conclude that I was experiencing channeling and that I was not getting good RIMS flow through the entire mash body. I always assumed the Blichmann false bottom did a pretty good job at avoiding channeling (Kai has a good writeup on fluid dynamics and why), but now I'm not so sure.
I ended up giving it a second major stir, and mashing for a little over 90 minutes, and the end result was 85% efficiency on a sizable brew. Some of this could be attributed to the longer mash, the finer crush I'm again getting, etc... but I have to say I will be giving my mash big stirs at two or three intervals from now on.
Has anyone else experienced channeling using a Blichmann false bottom? I'm curious to know other users' experiences. I will post updates with following brews to see if this single sample is statistically significant or an aberration.
I always assumed my RIMS system gave me a pretty efficient mash, but about 5-6 months ago, I experienced a more than 10% drop in my numbers. Concerned, I started learning more about crush, and water chemistry to try to figure out the problem and eliminate variables.
This weekend I did an experiment and saw my brewhouse efficiency jump to 85% on a 1.085 IIPA, which is not a small beer.
The background:
I have a single tier, three vessel, two pump system running a direct-fire RIMS mash. It's the basic analogue brutus10, with no automation. Once I had my system dialed in and I got into a good routine, I saw efficiency hovering between 77-79%, which I feel are more than respectable numbers for regular gravity beers. Higher gravity brews obviously result in a lower efficiency simply because most people don't feel like pulling 9 gallons and boiling 3 off in a 2.5 hour boil. We take less and leave residual sugars behind.
I digress.
When mashing, I use around 1.5 quarts of water per pound of grain. I dough in, stir to distribute and remove air bubbles, and let it sit for 10 minutes before starting my RIMS pump. I stir it again at the 5 and 10 minute mark because I learned the tiny trapped air bubbles on the grains and in the water eventually gave me cavitation issues. After implementing the pre-pump stir routine, that issue vanished.
My mash tun is a Blichmann 10 with the Blichmann false bottom. I love it; it's great. I can recirculate at a fast rate and not stick the mash. Good flow.
The mash filters itself pretty fast, with the liquid running cloudy, but debris-free within a minute or so. During the mash, the cloudy liquid eventually runs clear as the starch converts to sugar.
Several months back, as I mentioned, my efficiency dropped more than 10% and I started investigating. I eventually learned my LHBS widened the gap on its mill (I grind in-store), but the investigation process taught me about water chemistry, and my beers have benefited accordingly.
That's not relevant now, just background. Here's my issue: This weekend on the IIPA I decided on a whim to give the mash a stir after about 45 minutes. The liquid was running clear, I hit and maintained my temps, and am honestly not sure what possessed me to do it. The liquid flow became starchy cloudy again (definitely not particulate matter), and it didn't clear up for another 30 minutes.
I can only conclude that I was experiencing channeling and that I was not getting good RIMS flow through the entire mash body. I always assumed the Blichmann false bottom did a pretty good job at avoiding channeling (Kai has a good writeup on fluid dynamics and why), but now I'm not so sure.
I ended up giving it a second major stir, and mashing for a little over 90 minutes, and the end result was 85% efficiency on a sizable brew. Some of this could be attributed to the longer mash, the finer crush I'm again getting, etc... but I have to say I will be giving my mash big stirs at two or three intervals from now on.
Has anyone else experienced channeling using a Blichmann false bottom? I'm curious to know other users' experiences. I will post updates with following brews to see if this single sample is statistically significant or an aberration.
