The Gray Matala® filter media 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® 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® densities to achieve better solids removal or better biological filtering depending on the tank capacity. A Green piece next to a Gray piece for example will give good flow around the Gray one and trap solids in the Green one.
The various densities can be used in sequence or separately for unique filtration requirements. This is one of the greatest characteristics which Matala filters have to offer. No other media on the market can perform this step-wise filtration. Matala filter media effectively separates large particles to small and still maintains a very aerobic and free flow of water without channeling.