Pool Info: D.E. Pool Filters
D.E. filters are 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.
In addition to a monthly (+/-) backwashing, an annual or semi-annual maintenance cleaning is also required. After backwashing, drain the tank and remove the lid. The filter grids are removed and hosed off completely. Soaking the grids in DE filter cleaner will remove oils, minerals and stains, which can clog the filter fabric. DE grids are sometimes called elements, fins or septums.
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 fine mesh covered 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.
DE powder is what actually does the filtering. Diatomaceous Earth, specially graded for pool filter use (do not use garden-grade or food-grade DE), or you can use a DE alternative such as Perlite Powder, made with volcanic perlite. 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 are the microscopic skeletons of Diatoms, an ancient sub aquatic creature. Under the microscope, diatoms and perlite appear to be tiny sponges. This is where the dirt, oil and contaminants become trapped in your filter, within the powder.
Do not operate your filter 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 (Aqua Silk 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). 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 entire DE 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, and repeat this 3 - 4 times. Remember to always shut off the pump before turning your multiport valve or your push-pull valve. Each time you ‘bump’ the filter, or 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.
Separation Tanks: 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 waste) - 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. Separation tanks are an old idea that are making a comeback in areas under water restrictions.
Adding DE Powder: After backwashing, DE powder (or Perlite Powder) is immediately dumped into the skimmer to replenish what was just backwashed out. Try to add the powder within 60 seconds of turning the pump back on. You can pre-mix it with water, or just pour it dry, right into the skimmer, with the pump running of course. In cases where the skimmer is not working, a DE powder slurry can be poured into the pump basket, or even directly into the filter tank.
Measuring DE Powder: Because DE is so light, a pound of DE powder is more voluminous than a 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. Using a DE Scoop can make measuring more accurate.
Because backwashing only removes about 70% of the DE powder, add 1/3 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 SF DE filter may use 10 lbs of powder on start-up, but only 7 lbs after backwashing
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 the filter valve so that the water flows through the filter tank backwards, flushing out the dirt, hence the name "back-washing".
Before backwashing a DE filter, be sure to roll out the backwash hose, a flexible vinyl hose that is used as a discharge hose to carry the waste water out of the filter and to an area that can absorb the water without erosion problems. To prevent splits in the backwash hose, be sure it is not kinked, but laying nearly flat on the ground. The backwash hose should have a SS clamp to secure the vinyl hose to the hose adapter on the waste port of the valve.
DE filters can have either a push-pull valve (also known as slide valves) or a multiport valve. The multiport valve has multiple ports inside the valve, (hence the name) and usually 6 handle positions:
Typical Multiport Valve Positions:
- FILTER: Keep it here most of the time, except when backwashing, rinsing or wasting (draining).
- RINSE: Use this setting for 20 seconds after backwashing to rinse tank.
- RECIRCULATE: Use this if the filter is broken, at least you can circulate the water.
- BACKWASH: Use this setting to reverse the flow in the filter and send water out of the waste line. Make sure valves are open and backwash hose rolled out.
- 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.
- 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.
Properly sized D.E. pool filters 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 pH Decreaser solution for 15 minutes followed by a full rinse. Use 2 lbs of pH Down, added to 20 gallons of water in a large (clean) trash can. Or, use our D.E. pool filter cleaner, 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, missing air bleeder or other DE filter parts. It can also mean a broken air bleeder tube or assembly. There is usually a small gasket or o-ring on the top of the standpipe, known as the Standpipe O-ring, that needs replacement every so often, or it will leak DE powder into the pool. Finally, D.E. in the pool can mean that the multiport or push-pull valve is allowing powder to bypass the filter, requiring a new spider gasket, o-rings or other filter valve parts. 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, while you inspect the grids and manifold closely for any holes or cracks, which may require a disassembly of the grid assembly.
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 the top manifold. You can buy the entire set of 8 grids, DE grid sets 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.
You can also buy the entire DE Grid Assembly, which is all of the internal filter parts, already assembled, for a plug and play, drop-in installation. This is everything that comes out of the filter when you lift it out for cleaning. Complete Grid Assemblies include all of the DE grids, the top Manifold, the bottom Spreader Plate, and the long thru-bolts that tighten the assembly together. Replace the standpipe o-ring at the same time as replacing the grid assembly for complete DE filter rebuild. You can find o-rings and complete DE grid assemblies in our pool filter parts department.
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, requiring multiport valve parts to repair or a valve replacement. Large holes in the grids or cracks in the filter top manifold could also allow water to bypass the filter, albeit a small percentage usually. 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. If your pressure rises rapidly after backwashing, remove the grids and clean them manually using a Filter Cleaner, and inspecting for grid or manifold damage or loose thru bolts. 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) may need to run their systems 24 hours per day. Most people filter about 12 hours per day, but it depends on your system. Undersized? Old? High pool use? Heavy debris load? Heavy sunlight? Warm water? Any of these factors call for extra filtering. If you are too frugal with the electricity, you may have to pay more in chemical costs. Pool pump timers can help you save wear and tear and reduce energy usage.
Leaking DE filter?
Clamp Band Leaks: Most D.E. pool 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. However, cleaning and lubricating the o-ring (Teflon lube) and repositioning the clamp band can often help seal up a leak. Some older DE tanks have an inner retaining ring or backing plate for the o-ring and the lid must be positioned at the indicator marks to make a leak-free seal. Clamshell type filter clamps must be installed very tightly – tap the clamp with a mallet around the edge as you tighten down the bolt, to help it seat fully. New style spring clamps should have all spring coil surfaces touching, with no open spaces between spring coils.
Filter Valve Leaks: You may notice your multiport valve leaking in one or more areas. If your push-pull valve is leaking out of the backwash port (where the hose attaches), the plunger either needs replacement or just a new set of o-rings. We carry replacement DE filter parts for all major (and minor) pool filter brands, but if you need replacement filter valve parts for your multiport or push-pull filter valve, like spider gaskets, rotor or plunger o-rings, handles, or valve rebuild kits – we’ve got those too. See the sand filter page for more information on multiport valve leaks. If you decide to replace your DE pool filter valve, know that DE valves and sand filter valves are not interchangeable. The In/Out ports are reversed on sand and DE multiport and push-pull valves, so be sure to buy only replacement DE filter valves, not one made for sand filters.
Filter Tank Leaks: 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 buy a new DE filter immediately. There is no safe and effective way to repair holes or cracks in the pool filter tank, and it could rupture at any time.