The Grate Perc is an advanced percolation assembly that uses surface tension and back pressure to operate. The surface tension over the small slits in combination with the pressure supplied by the base and umbrella holds the water in the grate. Smoke pulled up through the grate percolates through the water in a highly turbulent region, creating a very high level of percolation.
This is an advanced device recommended only for those with prior BYOTubes experience. With the grate installed on an umbrella percolator on an equipped base with water, put the perc chamber on top and pour some water in. You can fill to the top of the grate part for good results. Use caution when disassembling, as when the grate is removed from the pipe, back pressure is lost and the water will flow through the grates.