I thought I would share. This is the inside of my keggle after whirlpool chill. I purchased a March pump after Christmas, Saturday I connected it to my keggle to do a whirlpool chill. Wort was brought into the pump via pick-up tube. Wort went back into the top of the keggle. The flow was very gentle / slow. About 20 minutes the wort was down to about 95 degrees. Don't worry, I don't pitch at 95 degrees, just a point of reference. The ring in the bottom is approximately 8" in diameter and 2" tall. As you can see it creates a nice barrier/dam/area for the hops/trub to collect. In this picture wort is actually at a level above the bottom of the ring. The ring sits loose in the bottom, but the concave bottom helps keep it centered. My keggle also has a bottom drain that was closed and not used for the whirlpool chill, but is opened for clean-out and clean-in-place, very handy.
Problems or still on the to do list: Re-work the Pick up tube to get it a little lower into the bottom. My plumbing on the outside consisted of 1/2" x 1/16" wall) silicone tube. It liked to collapse a lot on the pick-up side. My plan is to plumb 1/2 copper in and out of the pump and continue to use the silicone as soft/flexible connectors between the stainless hose barb on the outside of the keg to the copper pipe. As you can see from the picture 1/2" x 1/16" slips over the 1/2" copper nicely. I am using copper to "prototype" my design. When I get settled on this, I will switch to stainless tube.
