I have a 10 gallon rubbermaid cooler fitted with a SS bulkhead fitting and ball valve. I have tried it fly sparging with a SS perforated false bottom, SS braid and Bazooka Screen.
The false bottom is only needed if you are fly sparging. As I have used both several times on the same recipe and gotton the same efficiency, I don't fly sparge anymore.
The bazooka screen is nice in that it is a lot stiffer than the braid so that it tends to stay in place. The tradeoff is that the holes in the screen are bigger so you tend to get more fines requiring a little more recycle.
The SS braid works great but can move around when stiring. It does give a clearer wort.
I tried a PVC manafold once with slits. Worked OK but got a lot of fines and grain husk in the first runoff and was more dificult to clean. I also had to take care not to hit it while stiring since it was not welded together. I would not recommend a manifold in a round cooler.
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