How DE Filters Work

Let’s start with a definition: diatomaceous earth (DE). Translation: basically, it’s crushed plankton.

DE is cheap: a huge heavy bag is still only about 8 dollars at our local store. And, it’s a fantastic filtering medium for pool water. Water filtered through a DE filter is cleaned down to particulates of 5 to 8 microns in size. By comparison, a paper filter or sand filter removes only particulates of about 40 microns (or 30 microns once the sand gets a bit dirty).

Here’s how a DE filter works: A DE filter is comprised of an array of tubes which support a mesh fabric around them. The mesh is very fine, and so the DE introduced to the filter is pressed against the mesh fabric by the water pressure of the pump, but the DE does not pass through the mesh. The DE forms a shroud around the tubes, and together the system provides a very thorough and effective filtering system.

DE is changed every few weeks or months, depending on the season, the weather, how much rain or debris is introduced to the pool, and how much use the pool gets.

Here are some tips:

Watch the pressure gauge on top of your filter. It’s there to let you know when the filter is dirty. When the DE is completely encrusted with debris, water does not pass through as easily, and the water pressure rises. That’s when it’s time to clean the filter.

You clean a DE filter by backwashing, and forcing all the DE and debris out the exit pipe on your filter.

If you get cloudy water entering your pool through the return lines (the pipes that return water from the filter) you might have a torn filter (the mesh on the filter can rip or degrade over time). Don’t worry, you won’t need to replace the whole filter, just the fabric mesh.

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