[Joe T]

Correct, it's just a single variable in my system.
I'm not sure I understand how mash thickness matters to getting a good flow through the grain bed. Doing a full volume mash, my water/grist varies depending on the desired gravity. But because I have a whopping 2.5 gallons below my false bottom, my mash will be much thicker than someone with a very shallow false bottom, using the same ratio. Besides, with the amount of water being  the only variable, won't the thickness of a recirculated mash just settle in more or less the same each time, with the depth of the water on top simply getting deeper or shallower?

My crank and Stein mill is adjustable in increments of .005". It's now at .045. Crushing at .050 leaves some uncrushed grains so I'm as coarse as I can go.


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[BrewBama]

Not much difference between 1 gpm and .6 gpm is there!  What is that — maybe a 1/16” or even 1/32”?!  Wow.

I only mention the other variables in relationship with each other because that’s the way I operate my brewery.  I believe a combination of components and how they are used all contribute to the outcome. One change may or may not require other adjustments. A system of systems if you will.

I should also mention I use a Brew Bag as a mash filter as well as a false bottom (but it is not a traditional false bottom). It’s really just a baker’s cooling rack with large holes trimmed to fit simply to keep the mash bag off the bottom and allow good flow underneath. It is about 3/16” off the bottom of the MLT.

Another consideration is the inside diameter, material, length of hoses and number of elbows and valves in the plumbing. I have two five foot and one three foot 1/2” ID silicone hoses in my recirculating circuit. There are four 90* elbows and a RIMS tube which also contains two 90* turns. The entire system restricts pump flow therefore a different system will react accordingly.

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[mabrungard]

This is when a manometer plumbed into the bottom of the mash tun comes in handy. With the manometer reading, you can dial in exactly the flow rate your bed can handle. Minute turns of the valve can easily be seen in the manometer level.

[Joe T]

This is when a manometer plumbed into the bottom of the mash tun comes in handy. With the manometer reading, you can dial in exactly the flow rate your bed can handle. Minute turns of the valve can easily be seen in the manometer level.

The manometer definitely aids in fine tuning the flow. The slightest tweak on even a lowly ball valve is clearly indicated by a water level drop in the tube. Looking forward to trying it on an actual mash. Maybe next week...