Diatomaceous Earth Filters – What Is A Vacuum DE Filter?

A Diatomaceous Earth, or DE filter, is a type of disposable filter media. There are different ways in which DE is applied, each with their own pros, cons, and differences. A vacuum DE filter is one system utilized by Certified Pool Operators ® to maintain a pristine water supply at their swimming facility.

How It Works

DE is a white powder with sponge-like qualities that allow it to absorb large amounts of water. The particles are layered on top of one another to form a very fine screen to filter out even the smallest microns. The DE powder is held on filter elements called the septum. The septum is covered with a fine weave cloth material. 

During vacuum DE filtration, the powder forms the ‘cake’ on the septum while the gravitational flow of water holds the DE in place. The pool water flows by gravity from the main drain and surface to an atmospheric filter tank. After each filter cycle, DE media is discarded and replaced in a process called pre-coating. 



The replacement of used DE powder in a vacuum DE filter is a process called pre-coating. To start a new filter cycle, the filter tank must be drained and the soiled DE powder is collected and discarded. The filter tank is isolated from the pool by valves and the water is drained with an auxiliary pump. 

As the water is pumped out, the grids become exposed and the pool operator will use a hose to dislodge any remaining powder. The filter tank water and used DE should be pumped into a separation tank to collect the used DE powder. Never use sewers or open bodies of water to dispose of DE  

The filter tank is then filled with pool water by opening the control valves. The auxiliary pump is then re-valved to circulate the filter tank water. New DE powder is mixed into a bucket of water to make a slurry which should be added evenly around the surface of the filter tank. The Certified Pool Operator ® will look for a consistent color that indicates an even distribution of DE The main circulation pump is started before the auxiliary pump is turned off, completing the pre-coating process.

Applications & Benefits

Vacuum Diatomaceous Earth filtration is best used on larger pools, as they are able to contain large amounts of surface area within a small process unit. The system is great for commercial swimming facilities and especially large residential pools. Vacuum DE filtration is great for busy periods at a swimming facility where the increased amount of swimmers puts extra stress on filtration systems. One unique benefit of Vacuum DE filtration is how the open tank lets pool operators view the elements of filtration, allowing them to more accurately gauge the filter’s condition and performance.


One challenge Certified Pool Operators ® face when using a vacuum DE filter is how improper amounts of DE powder can result in ineffective filtration. Too little powder allows oils and debris to clock the filter’s openings, reducing the flow, eventually causing grid damage. Too much powder can result in the DE cake from one grid to come into contact with an adjacent grid. Vacuum DE filtration can also be more expensive than other options. However, the strain on your budget will allow for a much cleaner pool.


Learn More About The Vacuum DE Filter

To learn more about the DE filter and more, go to the experts at Pool Operation Management. The CPO® certification class is a great start to becoming a pool expert. Our award-winning pool operator training courses show you how to properly operate a swimming pool or spa facility. Our two-day courses offer a wealth of information and training in everything from pool chemicals to energy conservation to risk and liability. For the very best in pool operation, contact us today.

*This information is obtained from the Certified Pool and Spa Operator Handbook. This information may not be applicable to your pool based on your pool type and location. One should reference all applicable regulations and standards for your facility.

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