BioLab Info

THE DIATOMACEOUS EARTH (D.E.) FILTER

How It Works

With this filter, D.E. powder is used to strain debris from the water. D.E is the fossilized remains of plankton (diatoms), ground into a very fine powder. The D.E. powder coats the filter grids (the fabric covered structure within the filter).

These grids must be pre-coated with D.E. for the filter to work. To pre-coat the grids, make a solution with D.E. and water that's the consistency of similar to watered-down pancake batter. Pour this solution into the skimmer while the pump is running. Once the grids are coated, water passing through the D.E. is filtered better than with any other type of filter. The result is finely polished, sparkling water.

Advantages in choosing D.E. filters:

Removes particles as small as three to four microns for the cleanest water
Greatest ratio of filter surface area-to-water
Highest quality

Physical Cleaning

When filter pressure rises 10 to 15 psi above normal, it's time to clean the filter. (Note from Pool Emporium, Inc.: Our experience in Florida has shown that most pools do not reach a pressure increase of 10-15 psi, but are in need of backwashing. We suggest backwashing at an increase of 3-5 psi or every two months, whichever comes first.) With a D.E. filter, "cleaning" could mean a couple of things. It could mean:

Regeneration of the D.E. surface area without changing the D.E.
Backwashing the D.E., cleaning the grids, and recharging the filter with D.E.

Regeneration of the D.E can be done many ways, depending on the manufacturers design of the filter. Some filter grid assemblies are "bumped" and some are "spun." Ultimately, the result of these processes causes the D.E. powder to be "stirred-up" or knocked loose from the grids in the filter tank when the pump is turned off. When the pump is turned back on, the D.E. powder re-coats the filter grids with a "new" D.E. surface area exposed to do the filtering.

A pool owner regenerates the D.E media when filter pressure begins climbing 10 to 15 psi over normal, clean operating pressure (Please see Pool Emporium, Inc. note above). After regeneration, the filter pressure should be reduced by at least 5 to 10 psi. When the pressure still stays high even after regeneration it may be time for backwashing the D.E. powder, or chemically cleaning the grids and re-coating the grids with new DE. (Note from Pool Emporium Inc.: We feel there is no "may be" about it. Absolutely backwash the filter, and chemically clean it at least once per year and additionally when filter pressure cannot be relieved by backwashing when there are no apparent system problems.)

Backwashing the D.E. filter accomplishes much the same task as in a sand filter. Reversing the flow of water loosens the dirty D.E. and debris attached to the grids. This dirty D.E. is washed out of the filter tank and out the waste/backwash line. Since this waste water contains the D.E. powder, which is not degradable, many municipalities require separation tanks to be installed on the backwash line to capture the D.E. powder. This prevents the powder from accumulating in the sewer systems.

Chemical Cleaning

Every time you backwash the grids of a D.E. filter, it's important to chemically remove oils and stubborn organic debris that was not removed during the backwash cycle. (Please see Pool Emporium, Inc. note above.)

In a chlorine/bromine treated pool, Strip Kwik™ is used to remove oils. A follow-up cleaning with Kleen It™ is necessary to remove scale and other organic debris. (NOTE FROM POOL EMPORIUM, INC.: We do not suggest using Kleen-It™ on your filter unless it is necessary. Doing so will more permanently set any oils that have not been completely removed by a thorough cleaning. You may test your filter to see if it needs this second step by placing a few drops of acid on the pleats. If it bubbles, use the Kleen-It™, if it doesn't don't!) In a, biguanide (SoftSwim) pool, SoftSwim® Filter Cleaner™ is used to soak the filter grids in order to remove the residue specific to biguanide chemistry.

Once the D.E. filter grid assembly has been backwashed and chemically cleaned, follow the pre-coat process. Use one pound of D.E. for every 10 square feet of filter surface area. Mix the D.E. in water to form a solution and pour it through the skimmer. BioGuard® Sparkle-Up™ can greatly extend the filter cycle of a D.E. filter. (A filter cycle is the time the filter operates at peak performance between cleanings. This occurs before the filter begins clogging up, increasing filter tank pressure and reducing the flow of water back to the pool.) Mix one pound of Sparkle-Up for each three pounds of D.E, mix with water and add to pre-coat the filter grids. The Sparkle-Up/DE mixture will remove even smaller particles than D.E. alone and extend the filter cycle. The result is less frequent pool maintenance for the pool owner.

A pool owner using a properly sized D.E. filter and a chlorine or bromine maintenance system may only have to perform the backwash and chemical cleaning process once or twice a year (Please see Pool Emporium, Inc. notes above). A pool owner using SoftSwim® will need to backwash and chemically clean the filter at least every four to six weeks.