Has anyone tried a plenum in a FW tank?l

[Louis Z]

I put in Lava rock on the bottom of the plenum then wrapped a plastic light screen with landscape fabric to keep the 1.25 inch sand layer from falling thru. I then put another layer of landscape fabric on top of the sand and then put small gravel the size of pea gravel on top. Just wondering if anyone has used a plenum in fw. Thanks, Louis Z.