why suspend mash when sparging?

[todd_k]

Why do you have to suspend the mash when sparging? As long as your are running water through it and draining water out a spigot on the bottom, why can't the mash be held in a grain bag while resting on the bottom of the bucket?

 

[ajf]

Sparging is nothing more than rinsing the sugars from the grains. To do this, you want the sparge water to percolate evenly through the grains, and not develop channels which would rinse out the sugars in the vicinity of the channels, but leave much of the grain unrinsed. (You would create a channel leading to the spigot, and leave much of the lower grains unrinsed.)
Also, as sugar is heavier than water, you dont want to rest the grain bag on the bottom of the tun as the sugars would collect below the spigot, and you would get very poor efficiency.

-a.

 

[todd_k]

but wouldn't the sugars collect below the spigot anyway since the spigot of a bottling bucket is not on the very bottom of the bucket?
I guess I could set a collander inside the bucket which would keep it 1-2 inches off the bottom but the collander isn't all that big and the grain bed wouldn't really spread out across the entire circumference of the bucket.

 

[david_42]

When I do mini-mashes, I use a very large grain bag (as big as the tun). All I do at the end of the mash is add some hotter water, stir gently and then lift the bag out and let it drain. You could certainly have channelling if you leave the bag on the bottom of the kettle, or the sparge water could just run across the bag and out the spigot.

The weight of the sugars won't matter when water is flowing by.

 

[ajf]

but wouldn't the sugars collect below the spigot anyway since the spigot of a bottling bucket is not on the very bottom of the bucket?
I guess I could set a collander inside the bucket which would keep it 1-2 inches off the bottom but the collander isn't all that big and the grain bed wouldn't really spread out across the entire circumference of the bucket.

But if the grain bag is suspended above the level of the spigot, you can recover most of the wort in tha dead space simply by tipping the tun in the direction of the spigot.

-a.

 

[mpetty]

It is only an issue when fly sparging, because as mentioned, you do not want to develop channels.

You can avoid the entire issue by batch sparging, and achieve the same efficiencies. Do a Google search.