Super High Density Grey Matala 48" X 39" X 1.97" The Grey Matala® Filter mats will filter out a much smaller particle and yet still maintain good flow distribution. In larger systems all four types can be used in sequence to essentially remove all solids. Matala media works perfectly with upflow filter designs. The ideal configuration would be the Matala® filter media stood vertically rather than flat. This allows for easier cleaning. All you do is grab an individual piece and shake it up and down to clean it. If your filter chamber is packed to tight, take out one piece first. Laid flat you will have to remove all the pieces to get to the bottom dirty piece. Stagger your vertical pieces with different Matala mat densities to achieve better solids removal or better biological filtering depending on the tank capacity. A Green piece next to a Grey piece for example will give good flow around the Grey one and trap solids in the Green one.