First fly sparge, stuck. 5Gal. Igloo w/false bottom

[avshook]

I finally made a MLT out of a 5 gallon Igloo drink cooler and a 9" SS false bottom and attemped my first real fly sparge. It stuck badly after 4 quarts of recirculation and 4 quarts of run-off. The grain bed was completely compacted, like a 8" thick concrete disc. I use a Corona grain mill, and even though there are plenty of whole husks and big barley chunks in my grind, there is some flour in there as well. My guess is that the amount of flour in the grind, sparging too fast, and too much water above the grain bed are what made the sparge get stuck.
My question is, how slow is slow enough for a fly sparge? Should I be looking for a slow drip? That seems ridiculously slow, but will it help?
And, after the mash-out, should I let the level in the cooler drop to almost the grain bed before starting to add the sparge water?
And, do rice hulls actually help fluff up the grain bed?

If you use a similar rig, let me know how it goes for you.

 

[HoppyDaze]

I have the same set up and yes, rice hulls make a huge difference...

 

[patrck17]

Wow I never realized how bad it could be. I guess this is a result of fly sparging only because as a batch sparger I have never even come close to a slow or stuck sparge, and I grind my grains really fine. When I open up the ball valve the wort comes pouring out and is usally done within a minute.

I suspect this is because I am stirring the grains up between each batch sparge, I do two. I will have to take this into consideration if I decide to move into a fly sparging system, which I had actually considered.

I had always heard fly and other sparging methods taking an hour or more and I could never understand it since batch sparging is so fast, but I guess that has something to do with it.

 

[Yuri_Rage]

It should take about 45-60 minutes to fly sparge a five gallon batch. The resulting flow rate is one quart every 2-3 minutes.

 

[95747brewer]

I've wondered about this. When I fly sparge at low rates I can't seem to get the grain temp to rise even when sparging with 180 deg water. It seems like the tun is loosing more heat from being open than the sparge water is providing. When I sparge quickly I get the grain bed right up to just under 179 fine. Any input on this?

 

[Frank99]

It takes me 60 minutes to fly sparge 5 gallons. I set my hot liquor tank at 175 degrees and cover the top of the mash tun tightly with aluminum foil. There's very little heat loss this way. I set my BC at 30 and have never gotten a stuck sparge.

 

[ghack]

I've found when fly sparging the temperature can dip quite a bit without any appreciable loss of efficiency.

Rule of thumb flow rate is good, but you need adjust it for the amount of grain and for the grain bill. I find it work well to start slow and gradually increase the flow once the bulk of the sugars are rinsed out.