Cause of Stuck Sparge?

[planenut]

I was brewing a 10 gallon batch of Dry Irish Stout and had a problem with the recirculation system on my HERMS. After about 10 minutes, it would no longer circulate through the pump. I could clear it but it by stirring but it would only go for a minute or two before stopping again. When I stirred it, the bottom was pretty solid and would come up in clumps and them break apart. I have an igloo cooler with a stainless false bottom and a pump to recirculate through the coil in the HLT. I think the flow was slow enough and have not had this problem before.

The recipe was:
8 lbs 12 oz Marris Otter
1 lb 8 oz Roasted Barley
6.4 oz black barley
4 lbs flaked barley
1 lb flaked rye

I ran the MO, roasted barley and black barley through the barley crusher and then I ran about a 8 oz of the flaked rye through the barley crusher before stopping and didn't run the other 4.5 lbs of flaked grains through the crusher.

I ended up mashing around 148 instead of 150 because of the circulation problem. Do you think crushing the flaked rye caused the stuck sparge or something else?

 

[gturner6ppc]

I'm interested to know the answer myself, as I encountered sticky clumps yesterday in a layer from about two inches to six inches off the bottom. Once I removed that section everything went okay.

I shoud mention that I was running a strange experiment with a 30 inch grain bed in a 1-5/8" clear tube which was at an angle - so the height was still only about 8 inches. I'm trying to see how the grain bed behaves under different conditions.

 

[planenut]

After I finished sparging and draining the MLT, I did notice a brownish sludge on top of the grain.

 

[JuanMoore]

Not sure about the brown sludge, but flaked rye is really really sticky. I recently did a RyePA using both malted and flaked rye. I used 1/2 lb of rice hulls to help prevent a stuck sparge, and about halfway through it started draining really slow. I'd probably use a full lb of rice hulls if I do it again.

 

[gturner6ppc]

Years ago I tried adding Polyclar before lautering, thinking it would clear things up faster. I pulled lots of gunk out of solution - and deposited as an impermeable layer in the grain bed.

From that experience I learned what not to do, and later stuck lauters led me to conjecture that perhaps subtleties of chemistry, static charges, temperature gradients, and the like could lead to a rapid deposition of trub in the grain bed. I don't know if this is true, but it is a more interesting explaination than blaming things on wort gremlins.

Then again, yesterdays experiment merely confirmed to me the existence of those very gremlins.

 

[planenut]

Well hopefully it was just the rye or maybe some really dry grain.

Next time I will condition the grain and add some rice hulls as well. It was a royal pain not to be able to run the HERMS after the investment in time and money. Not to mention the stress of wondering if it would drain into the kettle...