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What is a DE Pool Filter?

Types of Swimming Pool Filters


Canada, British Columbia, Surrey, back yard of house with pool at dusk Ivan Hunter/Digital Vision/Getty Images

DE Pool Filters:

DE stands for diatomaceous earth, which is sedimentary rock composed of chemically inert, fossilized (or skeletal) remains of billions of microscopic organisms, called diatoms. There are three types of filters used for pools: sand, cartridge, and diatomaceous earth (DE).

Many pool owners and pool maintenance workers consider DE filters to be the best type of filter for residential swimming pools. Why? Among their advantages, DE filters are compact and filter out smaller particles than the other types of filters.

Why is Diatomaceous Earth Used for Pool Filters?:

DE, the abovementioned white powdery substance, is similar to dinosaur bones, according to pool expert Terry Tamminen, author of The Ultimate Guide to Pool Maintenance. If you examine diatomaceous earth (DE) under a microscope, maintains Tamminen, you'll see tiny spongelike organisms -- which explains DE's ability to absorb or filter water's impurities. Since the DE is so fine, it can filter extremely small -- microscopic-sized -- particles from the water as it passes through.

Where can I buy diatomaceous earth?
DE can be purchased at hardware stores, pool supply stores and grain and feed supply stores.

What is food-grade diatomaceous earth?
Food-grade DE does not mean you'll be serving up DE burgers at your next barbecue. Don't even think about it. Fresh-water food grade diatomaceous earth is the type used in agriculture for grain storage, and as feed supplement for livestock and farm animals.

Do most cities allow the use of DE as a pool filter?
Because DE could potentially clog pipes, some cities and counties do not allow it to be dumped into sewer systems. Instead, a separation tank is added next to the DE filter. When the filter is drained or backwashed, the dirty water passes through a canvas strainer bag inside a small tank before reaching the sewers or storm drains. Most of the DE is retained in the strainer bags, which can then be discarded.

Is this the same diatomaceous earth used to control bed bugs and fleas?
DE has long been used for pest control because that fine, absorbent powder causes insects' exoskeletons to dehydrate and die. DE can be found in snail and slug repellents, and is used to control cockroaches and fleas.

And yes, the infamous bedbug can be eradicated by DE, although it can take several weeks to do the job.

What are other uses for diatomaceous earth?
DE is also used in cat litter, to filter drinking water, in fish tanks and in beer and wine. Diatomaceous earth is sometimes used to filter syrup, sugar and honey.

Because of its abrasive properties, DE has been used in toothpaste, metal polishes and facial scrubs. Other uses for DE include:

  • As an ingredient in bonsai soil
  • As a growing medium in hydroponic gardens
  • As an additive in cement
  • Dewormer
  • A filler in many products such as paints and dry chemicals
  • In chemistry as a filtration aid

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