Imagine your pool water is crystal-clear, without any debris in it – not even the tiniest speck of sand or dirt. You might ask yourself if this is even possible. With a D. E. filter, it is possible. D. E. Filter Facts Some people have never heard of D. E. filter technology. D. E. stands for diatomaceous earth – an abrasive sediment made of fossilized skeletons that picks up the finest of debris. Diatomaceous earth is used in many different products for its excellence in filtering and purifying water. In the pool industry, it’s known as one of the best available options for filtering pool water because of its ability to trap particles as small as 2 to 5 microns. For reference, bacteria is sometimes as large as 3 microns, so some of these particles aren’t visible to the human eye. Whether you have a spa or a pool that needs filtering, D. E. filters are a great option for fast, reliable filtering.