Pool Perfect with PhosFree Hayward Perflex D.E. Filter-Above Ground Diatomaceous Earth Filter Powder D.E. Pool Filters

The D.E. filter is the most efficient type of pool filter available to pool owners. It can trap particles down to 3 - 5 microns; well below what the naked eye can see, which is around 35 microns. DE filters, like most pool filters, use a pressure gauge to indicate the need for backwashing; when it reads 8 - 10 lbs. higher than the clean, or start-up pressure. After backwashing a D.E. filter, the dirty filter powder is discharged, and a new application of D.E. filter powder is added to the filter by pouring it into the skimmer.

De Pool Filter

In addition to monthly backwashing, an annual or semi-annual maintenance cleaning is also required. The tank is drained and opened and the filter grids are hosed off completely. A chemical soaking of the grids in DE filter cleaner will remove oils, minerals and metals, which can clog the filter fabric. DE grids are sometimes called elements, fins or septums.

DE powder is what actually does the filtering. The filter grids inside of the filter tank are the holder for the powder, and without DE powder to coat them, can clog up in under an hour. D.E. stands for diatomaceous earth, which is a widely available, inexpensive powder; actually the microscopic skeletons of Diatoms, an ancient, sub aquatic creature. Under the microscope, diatoms appear to be tiny sponges. This is where the dirt gets trapped in your filter.

DE powder, when added to your skimmer, dissolves in the pipe on its way to the filter tank. When it reaches the grids, which are covered with a woven polyester type of fabric, the powder stops, coating the grid. The water continues to pass through, first through the powder, then the fabric covered grid. As the water passes through the D.E. and enters the grid it leaves behind the dirt, trapped in the D.E. powder "cake" or coating. The powder is the filter.

Do not operate your pump without having the D.E. powder coating the grids, or you will see the filter pressure rise very quickly, and if left in this manner the grids can collapse or the fabric can become clogged or damaged. As the pressure gauge on a D.E. filter increases, flow rate decreases. Eventually the lower flow rate causes the water quality to suffer. You will need to backwash the filter to remove the D.E. that is clogged up with the dirt. After backwashing thoroughly, add new D.E. powder to the filter through the skimmer.

Cleaning DE Grids: If using biguanides (Soft Swim or Baquacil) you will need twice annual, very thorough cleaning to prevent it from gumming up. Chlorine D.E. filters should have this done at least once per year. Thorough cleaning is accomplished by turning the pump off and draining the filter, after backwashing. Remove the tank top half, and remove the grid assembly to a cleaning location. Hose the grid assembly thoroughly to remove all dirt and DE powder between the grids. For an extra good job, after hosing, soak the assembly in a trash can filled with water and a DE filter cleaner product (or use TSP {tri-sodium-phosphate} from the hardware store). Rinse thoroughly before reinstalling grids into tank.

Inspecting DE Grids: While cleaning the DE grids, it's good to inspect the fabric for tears and holes. Holes in your DE grids larger than 1/4 inch can be sewn, or the grid replaced. Inspect also for mis-aligned grids, so that the spaces between the grids are all consistent. Check that the through-bolts are tightly secured so that the grid assembly is drawn close and the grids are tightly locked into the top manifold and the bottom spreader plate.

Bumping a DE Filter: When backwashing a D.E. pool filter, bump the filter several times. That is, backwash until water runs clear, shut off pump, and move the multiport valve to FILTER and run it on filter for a 10 seconds, then backwash again until it runs clear, etc...do this 3 - 4 times. Remember to always shut off the pump before turning your multiport valve or your push-pull valve. Each time you go through the cycle of filter/ backwash/ filter, you will get more dirt/ D.E. out of the filter, giving you a better, more thorough backwash.

Be cautious not to pump DE waste water directly into streams as it may choke small aquatic life. Your city or town may have discharge regulations for DE powder.

If you are using a separation tank for backwashing, or a separate tank that separates the DE from the waste water, and returns clean water to the pool (prevents water wasting) - it is especially recommended to bump the filter as described above, and run your backwash cycle for a longer time period, maybe 10 minutes. Using a sep tank may also require more frequent manual cleaning of the DE grids, because the backpressure reduces the overall flow rate during backwashing.

Also important in ensuring an effective backwashing is to make sure skimmer baskets and pump baskets are clean to allow for full flow entering the filter.

Adding DE Powder: After backwashing, DE powder is immediately dumped into the skimmer to replenish what was just backwashed out. In cases where the skimmer is not working, a DE powder slurry can be poured into the pump basket.

Because backwashing only removes about 70% of the DE powder, add a third less powder than you would add when starting up a cleaned filter, empty of DE powder. For clean filters, add 1 lb of DE powder for each 5 sq ft of surface area. For example, a 48 sq ft filter may use 10 lbs of powder on start-up, but only 7 lbs after backwashing.

Because DE is so light, a pound of DE powder is more voluminous than 16 oz liquid measurement. The common standard of measurement for 1 lb of DE powder is the 1 lb coffee can, or about 4 cups, if using a kitchen measuring scoop. Not adding enough DE powder will give you a shorter filter cycle. Adding too much DE will cause the DE cake to bridge between grids, resulting in loss of efficiency.

How do I Backwash my DE Filter?

When the pressure gauge is reading 8 - 10 lbs above the clean, starting pressure (after backwashing), it is time to backwash the filter. This process involves moving a valve so that the water will flow through the filter backwards, flushing out the dirt. Hence the name "back-washing".

DE filters can have either a push-pull valve (also known as slide valves) or a multiport valve. The multiport valve has multiple ports on the valve, (hence the name) and usually 6 handle positions:

  1. FILTER: Keep it here most of the time, except when backwashing, rinsing or wasting (draining)
  2. RINSE: Use this setting for 20 seconds after backwashing to rinse tank
  3. RECIRCULATE: Use this if the filter's broken; at least you're circulating your pool water.
  4. BACKWASH: Use this setting to reverse the flow in the filter and send water out of the waste line. Make sure valves are open or discharge hose rolled out
  5. CLOSED: Put here to close off flow from the pool, usually to work on the equipment. Do not operate pump with valve in closed position
  6. WASTE/ DRAIN: Another filter bypass setting, this setting sends the water out of the waste pipe (hose), instead of returning it to the pool. Used to lower pool water level or to vacuum to waste

To backwash a D.E. filter with a multiport valve:

  • Shut off pump motor
  • Press down on valve handle, rotate valve from FILTER to BACKWASH position
  • Roll out any backwash hose or open any waste line valves
  • Open air bleeder assembly on filter, and turn pump on.
  • Watch pressure gauge for backpressure and hose for kinks. Be prepared to shut off pump quickly
  • After hose fills with water, run for 2 - 3 minutes or until water runs clear
  • Shut off pump motor and move multiport valve handle to RINSE position. Run on rinse for 5 - 10 seconds. Shut off pump again, and move handle back to BACKWASH. Turn on pump again until water runs clear. Continue in this fashion 3 - 4 times, alternating between Backwash & Rinse (or Filter), to ensure a thorough backwash.
  • Shut off pump motor and move multiport valve handle to FILTER position
  • Turn pump back on and note lower pressure. Roll up backwash hose
  • Add 1 lb D.E. powder per 10 sq ft of filter area. Look on filter tank for filter area

To Backwash a D.E. filter with a slide valve:

  • Shut off pump motor, roll out backwash hose (if you have it)
  • Twist to unlock plunger T-handle, pull/ twist plunger upwards 2 - 3"
  • Open air bleeder assembly on filter, and turn pump on
  • Watch pressure gauge for backpressure (+ 30 PSI) and hose for kinks. Be prepared to shut off pump quickly.
  • After hose fills with water, run for 1 - 2 minutes or until water runs clear. Shut off and push handle back down. Turn pump on and run in filter position for 15 seconds and then shut pump off and backwash again for 1 min. Filter again for 15 seconds and another 30 second backwash.
  • Shut off pump motor and push T-handle back down into locked position
  • Turn pump back on and note lower pressure. Roll up backwash hose
  • Add 1 lb D.E. powder per 10 sq ft of filter area. Look on filter tank for filter size.

A properly sized D.E. filter should, in most cases, be able to operate continuously for a period of 4 weeks between backwashing. A "Filter Run" of less than 4 weeks may indicate grid problems (or sizing problems). It can also be a sign that too little or too much DE powder is being used.

Filter grid fabric can become clogged with Calcium deposits or oils. After removing the grids from the assembly, you can soak in TSP (trisodium-phosphate) and warm water to remove oily deposits. If you have high levels of calcium or other minerals in your pool water you can soak the grids in a 10% muriatic acid solution for a few minutes followed by a full rinse. Or, use one of the many pool filter cleaner products available, which removes both oils and minerals.

D.E. powder in the pool?

It’s not unsafe, and you can continue swimming, but if you notice a tan colored substance on the pool floor, which ‘poofs’ when you touch it, it’s likely DE powder. The grids may have holes in the fabric, or there may be a crack in the manifold that the grids attach to. It can also mean a broken air bleeder tube or assembly. Finally, D.E. in the pool can mean that the multiport or push-pull valve is allowing powder to bypass the filter. You will notice this most when adding new D.E. powder after backwashing, but you can test this at any time. The best method to determine the cause is to remove the grids and clean/ inspect thoroughly.

Filter Grid replacement

Grids and manifolds vary by manufacturer, and by size. DE grids are usually $10-20 per grid; and you may expect to pay $50-100 for a manifold. Labor is usually under one hour. You can buy the entire set of 8 grids for a lower price than buying them individually, and many times it is best to replace all the grids at one time. When replacing all the grids, do it upside down, with the manifold on the ground, and then work the bottom spreader plate on the top, spacing all grids correctly. Tighten up the through bolts to sandwich the grids tightly between the manifold and bottom spreader. If handy with an awl, torn grids can be sewn instead of replaced.

Poor water Quality?

It could be a problem with your multiport or push-pull valve. The valve could be allowing water to bypass the filter and return to the pool unfiltered. Perhaps you are not running the filter pump long enough each day. Perhaps there is not enough D.E. powder in the filter, or too much DE powder. You may also need to backwash the filter or remove the grids and clean them manually, inspecting for damage. Poor sanitation, poor water balance, and poor circulation could be another cause, and it could have nothing to do with the filtering at all.

How long should I run my DE pool filter each day?

Well, just as much as you need. Careful experimentation will show you when the water quality begins to suffer. Many people with smaller, older equipment (filter/ pump) run their systems 24 hours per day. The average (I would guess) would be about 16 hours per day, but it depends on your system. Undersized? Old? High pool Use? Heavy Debris Load? Heavy Sunlight? Any of these factors call for extra filtering. If you're too frugal with the electricity, you may have to pay more in chemical costs.

Leaking DE filter?

Most D.E. filters have a belly band clamp with a large O-ring between tank halves. The o-ring can become distended or flattened and may need to be replaced if water is dripping from the center clamp. Caution: Do Not remove the center clamp while the pump is running, and without first releasing pressure inside the tank. You may notice your multiport valve leaking in one or more areas. See sand filter page for information on multiport valve leaks. If your push-pull valve is leaking out of the backwash port (where the hose attaches), the plunger either needs replacement or a new set of o-rings.

If your DE filter tank is leaking, and not from the belly band, bulkhead fittings or air bleed assembly, but in the tank itself, through a pinhole or crack, replace the tank half or entire filter immediately. There is no safe and effective way to repair holes or cracks in the pool filter tank.

Related Products:

DE Filter Cleaner
DE Filter Parts
DE Grid Sets
DE Powder

Related Blog Posts:

Annual D.E. Filter Cleaning & Inspection
Common DE Pool Filter Repairs
D.E. Pool Filter Grids Care & Repair
How to easily replace DE filter grids