What is a Diatomaceous Earth (D.E.) filter and how does it work?

What is Diatomaceous Earth? 

Diatomaceous earth (D.E.) is a naturally occurring, soft, sedimentary rock that is composed of the fossilized remains of tiny, single-celled aquatic organisms called diatoms

DE Filter

In swimming pools, D.E. is added to a filter tank that contains a grid or a set of fabric-covered grids. The pool water is then passed through the D.E. and the grids, which traps dirt, debris, and other contaminants. As the pool water passes through the D.E., the microscopic pores of the diatomaceous earth capture particles as small as 2-5 microns in size, resulting in crystal-clear pool water.

D.E. is an effective filter media because of its high porosity and its ability to capture very small particles. However, it can be messy to handle and requires periodic maintenance to keep the filter functioning properly. It is important to follow the manufacturer's instructions for handling and disposing of D.E. to avoid any potential health hazards.

How does a DE filter work?

D.E. filters work by passing water through a grid or a series of grids coated with D.E. powder. The powder coats the grids and forms a layer of filter media. As water passes through this layer, any particles or debris in the water become trapped in the D.E. The clean water then passes through the filter and returns to the pool.

How Diatomaceous Earth (D.E.) filters are different from sand filters?


Diatomaceous Earth (D.E.) filters and sand filters are two popular types of pool filters, but they work in very different ways.

The process of using sand filters in swimming pools involves passing pool water through a bed of sand, which acts as a filter to trap debris and particles. This allows the clean water to be returned to the pool while the trapped particles are removed from circulation.

In contrast, D.E. filters use a fine powder made from the fossilized remains of tiny aquatic organisms called diatoms to filter out impurities. The D.E. powder is added to the filter and coats a grid of filter elements inside. As water passes through the filter, the D.E. powder traps the impurities, and clean water is returned to the pool.

D.E. filters are generally considered to be more effective at filtering out small particles than sand filters and require less maintenance, but they can be more expensive upfront.

How to Backwash a D.E.  Filter

D.E. filters use a powdery substance made from fossilized diatoms to effectively trap dirt and debris. However, as this material accumulates over time, the filter can become clogged and hinder water flow. To restore the filter's efficiency and remove trapped dirt, backwashing is necessary. 

How to backwash a Diatomaceous Earth (D.E.) pool filter using a multiport valve:

  1. Turn off the pool filter system.
  2. Attach the backwash hose to the filter's waste port.
  3. Turn the multiport valve to the Backwash setting. In case of a push/pull valve, open the backwash gate.
  4. Restart the pool filter system and let it run for roughly two minutes, allowing the pool water to flow out through the backwash valve or port.
  5. Turn off the pool filter system.
  6. Set the multiport valve to Rinse and turn the system back on for about a minute.
  7. Turn off the pool filter system.
  8. Return the multiport valve to the Filter setting.
  9. Create a slurry by mixing the appropriate amount of D.E. powder with water and pouring it into the pool skimmer.
  10. Run the pool pump for at least 30 minutes to ensure even distribution of the D.E. powder over the filter grids.

Important Note: Turning the multiport valve handle while the pool filter is operational can cause severe harm or water leakage. The rubber diverter gasket inside the valve may dislocate or shatter, causing water to leak from unintended ports while the filter is still running. Therefore, it is essential to avoid turning the multiport valve handle while the pool filter is operating to prevent any damage or water leakage.

How much D.E. powder will you need to add in DE filter of swimming pool? 

DE Powder How much DE powder

It is recommended that you add an amount of DE powder equal to the amount added during the filter's startup during each backwash cycle. For instance, if you initially added 4 pounds of DE powder to a new filter, you should add approximately 4 pounds of DE powder for every backwash cycle. It is crucial to follow the manufacturer's guidelines for your specific DE filter, and seek advice from a pool professional if you are uncertain about the appropriate amount of DE powder to use during backwashing.

How to dispose of DE filter backwash water properly

To minimize environmental impact, it's important to avoid dumping filter backwash water into bodies of water such as streams or rivers. Instead, consider discharging the water into a sanitary sewer or septic system. If these options are not available, seek guidance from your local environmental agency on proper disposal methods to ensure responsible handling of the backwash water.