RIMS mashing and sparging - Bed never settles

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shortyjacobs

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So I've only had about 4 or 5 forays into the world of RIMS brewing and constant recirculation during the mash. I also fly sparge, which I had never done before.

On 2 batches, the grain bed settled down during recirc, so I had about 1-2 inches of clear wort on top of the grain bed, and during sparge it stayed that way.

On the other batches, the grain bed never settled down. The grain "floated", so no matter how much water I added during sparge, (i.e., how much I increased flow IN vs flow out), the whole grain bed just rose up, instead of getting that nice clear section of water/wort on top of the grain. (Note: the entire grain bed seems to decrease in density the more water I add...I don't just have a thin layer of grain floating on top of the water layer on top of the mash bed...the grain bed expands to fill all the water space...)

I'm using a copper sparge manifold, (a square with holes drilled in it), both for the recirculation stage and the sparging stage. Sparging a 11 gallon batch takes around an hour, so I'm running slow. During recirc, pump pulls from the bottom manifold in the cooler, sends wort through RIMS, then back into the cooler through the sparge manifold. During sparge, sparge water flows by gravity from my HLT into the sparge arm, wort is pulled from the bottom by the pump and sent to the BK. During recirc, pump runs wide open, full flow. During sparge, obviously pump is stepped down to a trickle, and water from HLT is at a trickle.

Should I be concerned? How do you make your grain bed settle so you have that region of clear water/wort on top? I stir to dough in, and not at all after that. Efficiencies in the mid-to-high 80s.
 
I'm not a RIMS brewer, but i have brewed on a RIMS. I'm not 100% what is going on here, but grain beds are supposed to float aren't they? How long are you sparging for? Perhaps you need to decrease your sparge time in order to get the water on top of the grain bed like you like it? If you're making good beer, and have consistent efficiencies in the 80s, seems like you're doing it right. Do be warned that if you do reduce your sparge time, your efficiencies will most likely drop.
 
Yeah, wort's crystal clear after that hour of recirc....it's very weird.

I haven't tried "raking the bed" yet....is that why maybe?
 
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