A DE Filter Grid is a key internal component of diatomaceous earth (DE) pool and spa filtration systems, responsible for capturing ultra-fine debris and maintaining clear, clean water. The filter grid provides the surface area needed for DE powder to coat evenly, forming a highly effective filtration layer inside the filter tank. As water passes through the DE filter system, contaminants such as dirt, algae, oils, and fine particles are trapped on the DE-coated filter grid while clean water is returned to the pool or spa.