The Black Pond Filter Mat ($200 \times 100 \times 8\text{ cm}$) is the absolute heavy artillery of pond and koi filtration. At a massive 8cm thickness, it is double the depth of standard mats, making it engineered specifically for extreme mechanical separation and heavy biological loads in large koi ponds, public water features, and industrial-scale sumps.

The color coding matters here: while blue mats are typically medium-coarse, black mats are generally engineered as extra-coarse, ultra-porous structural media meant to take the first and heaviest hit from pond debris without stopping your water flow.