How much room should there be under a false bottom?

[Extralike]

Hey,
So I started converting a rubbermaid style round cooler to a mash tun. I want to go for a false bottom made out of two pizza screens and a mash in between them to make a false bottom. My question is, how much room should I leave underneath? How high off the bottom of the cooler should I put the screens?

 

[Hello]

Mine basically sits on the bottom but it's domed. I have .20 gal of deadspace underneath.

 

[Jaybird]

Most all the systems I build for the coolers are built so the false bottom sits just above the spigot. The stands are 2" tall so I would think if you shot for the 2" mark you would be golden.

Cheers
Jay