What is a DE filter?

A diatomaceous earth (DE) filter is a pool filtration system that relies on finely ground powder made from fossilized diatom shells to capture debris, algae, and other contaminants from water. The DE powder coats filter grids or cartridges, creating a porous surface that traps particles as small as 3 to 5 microns, making DE filters among the most effective at keeping pool water clear.

The filter operates by drawing water through the DE-coated media, where particles become trapped while cleaned water returns to the pool. Over time, as the powder collects debris, water flow slows and pressure builds inside the filter tank. When pressure reaches the manufacturer's recommended threshold (typically 8 to 10 PSI above the baseline), the filter requires backwashing.

Backwashing reverses water flow through the filter to flush trapped sediment and old DE powder out through a waste line. After backwashing, fresh diatomaceous earth powder must be added to the skimmer or the filter itself to restore the filtering layer. This regeneration cycle is the defining maintenance task for DE filters, distinguishing them from sand or cartridge alternatives. Pool contractors in Naples can advise on whether a DE system matches a property's usage, water chemistry needs, and maintenance commitment.