Have you ever heard of a multimedia (multilayer) filter made of approx. the following layering for a 21" x 62" Poly tank:

400# 1/4" x 1/8" Gravel
200# #80 Garnet
100# #40 Sand
100# #2 Anthracite

Is this actually practiced or was it a fluke by the guy who put it together? This is a Marlo filter with a 3150 valve that I recently rebedded. It was a joke. The gravel, garnet and sand where all mixed together. Only the anthracite was stratified at the top.