Expanded Clay Aggregate (ECA) has numerous features that make it a perfect material for the construction of artificial wetlands. First, it’s lightweight, and the numerous tiny pores and holes in the clay allow for drainage and oxygenation. For this reason, it’s often used as a substrate in wetlands, particularly peat wetlands. ECA also has a very balanced pH and does not affect the acidity levels of the surrounding material, so it does not affect the natural processes, such as plant material decay, which take place in wetlands. It also is very stable and durable, so it provides an even platform upon which a constructed wetland can be built.