Cleaning a Pool DE Filter

DE Filters require a backwash cleaning every 4 - 6 weeks; this process cleans dirt that is caked on the filter elements. Backwashing is very easy, presents no complications, and can be done in less than 10 minutes. However, these filters need a yearly maintenance that involves taking it apart and cleaning the grids. A professional should do this because if it isn’t done properly, there are water pressure risks that can’t be ignored (I have seen a top blow off the filter and over a house!). A tech can also point out potential problems and show you the wear and tear of the filter elements.

Every DE and Sand Filter has a waste port that dirty water is pumped out from the filter. Some are just an open port, which splashes water all over the place. Others have a drain hose, app. 2” in diameter, attached to the exit port by a clamp (you can buy this hose at a pool store). Some filters have pipes permanently attacked to the exit port, which drains water into an out of the way area of the yard.

DE Handle Facts: Familiarize yourself with the DE control handle and the different settings before cleaning. NEVER, NEVER, turn DE handle while pump is running as it will destroy the gasket inside the handle, or worse, damage the equipment. The handle should always be set in the FILTER position unless you are cleaning the filter. Not all DE handles are labeled the same and may have 4 - 6 settings. The following photos should be used as a basic reference only.

What each setting means:

FILTER - used when pump is running to clean and circulate water
BACKWASH - cleans filter
RINSE - follow up after backwashing
WASTE- perfect for lowering the water level if too high. Keep a close eye on water because it drains very, very fast. Do not let water level go below the halfway mark of your skimmer.
CLOSE - use if water level is below the skimmer opening.
RECIRCULATE - this bypasses the filter if you have a filter problem and keeps water circulating in pool.

Now, let’s clean your DE filter…

Turn off motor. If you have a drain hose, make sure it is unrolled and lying flat on the ground. If it is twisted, water will back up into the system. Some systems have a drainpipe attached to the filter – make sure drainage area is clear with nothing blocking exit port.
Put control handle on BACKWASH, turn motor on and let run for about 30 seconds. You will see dirty water from the filter coming out the exit port or hose. There is a small glass vial on the side of the control handle. When you are backwashing, you will see this fill with dirty water from the filter; this allows you a second visual of the water changing from dirty to clean. Turn off motor.
Set handle on RINSE and let run for 15+ seconds. Turn off motor.
Return handle to BACKWASH, turn on motor and let run until water comes out clear (about a minute). Turn off motor.
Repeat steps 2 & 3 until the water runs relatively clear in BACKWASH mode. Your final rinse can run for 30 seconds or more if you desire.
With the motor turned off, move handle back to FILTER position. Remove excess water from hose by grabbing it by the exit port and squeezing the water out while walking along the length of the hose. Roll up hose and set next to filter. If hose fills with water when rolled up, there is a leak in the handle gasket.
Turn on motor and prepare to add DE powder (for DE filters only)

Adding DE Powder for DE Filters only (never use DE on a Sand Filter)

Powdered Diatomaceous Earth (DE Powder) are tiny diatoms of fossilized exoskeletons that coat the grids in the filter housing. They act as tiny sieves, which remove debris as small as five microns. Once the filter is backwashed it is “recharged” with DE powder, which is added through the pool skimmer while using a 48-oz scoop. Each scoop is equivalent to 1 lb. of DE powder and can be purchased at a pool store. They are the approximate equivalent of two 10 ounce coffee cans. In order to determine how much DE powder you should use, look on the side of your filter for the factory specifications displaying the square footage of the filter area. It will start with 24 and is listed in increments of 12. You will start with 2.4 scoops of DE powder for the first 24 feet and another scoop for every 10 square feet of filter area. The formula below is also listed on the DE powder bag:

24 Sq. Ft. Filter = 2.4 lb. = 2.4 scoops
36 Sq. Ft. Filter = 3.6 lb. = 3.6 scoops
48 Sq. Ft. Filter = 4.8 lb. = 2.8 scoops
60 Sq. Ft. Filter = 6 lb. = 6 scoops
72 Sq. Ft. Filter = 7.2 lb. = 7.2 scoops

Manufactures of DE filters recommend dissolving the DE powder in a bucket of water and slowly pouring it into the skimmer. Many pool techs just add the powder slowly into the skimmer with the understanding that no matter how you pour it in, the powder dissolves by the time it gets to the filter.

CAUTION: Do not breathe DE powder. Always wear a face mask and safety goggles. DE powder is typically purchased in 20 lb. bags. I encourage you to transfer it to a sealable container rather than working from the bag. Once in the container, I spray water onto the powder to keep the powder down. If you do this, don’t overdo the water, although you will be surprised to see how much water the powder absorbs.

DANGER: If you put off having your DE filter taken apart and cleaned professionally consider this: a pool owner called a local pool repair company because the top of his DE filter blew off, up, and over his house! This was a result of not properly backwashing once a month and there was excessive buildup of dirt, DE powder, and granular chlorine in the filter housing. Granular chlorine will build up in a DE filter if you use it constantly, even after back washing the filter. If you note a higher PSI reading on your pressure gauge, and it lowers only minimally after a backwash, call in a service professional to clean your DE filter properly.

Cleaning Sand Filters
Follow steps 1 - 5 of the DE cleaning procedure. IMPORTANT! Do not put DE powder into a Sand Filter as the powder expands in the housing and could burst the casing. Don’t ask me how I know this.