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The water is continuously cleansed by a sandfilter.

A valve on the top helps control the flow through the sandfilter.  Never turn the valve with the pump on.  Always turn the valve in a clockwise manner.

In normal operation it is in the FILTER mode.

When it is in the BACKWASH Mode, it will take water out of the pool and into the yard!!





"How do I Backwash my Sand 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 turning a valve so that the water will flow through the filter backwards, flushing out the dirt. Hence the name "back-washing." Sand filters can have either a push-pull valve (aka slide valve) or a multiport valve. The multiport valve has multiple ports on the valve, usually 6 positions:

  • FILTER: Keep it here 99% of the time, except when backwashing, rinsing or wasting

  • RINSE: Use this setting for 20 seconds after backwashing to rinse tank

  • RECIRCULATE: Use this if the filter's broken; at least you're circulating.

  • 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 hoses 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, but this one 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.

So, to backwash a sand filter with a multiport valve;
  1. Shut off the pump motor.

  2. Press down on valve handle, rotate valve from FILTER to BACKWASH position.

  3. Roll out any backwash hose or open any waste line valves.

  4. Open air bleeder assembly on filter, and turn pump on.

  5. Watch pressure gauge for backpressure and hose for kinks. Be prepared to shut off pump quickly.

  6. After hose fills with water, run for 2 - 3 minutes or until water runs clear.

  7. Shut off pump motor and move multiport valve handle from BACKWASH to RINSE position.

  8. Run on rinse for 15 - 25 seconds.

  9. Shut off pump motor and move multiport valve handle from RINSE to FILTER position.

  10. Turn pump back on and note lower pressure. Roll up backwash hose.


Working with your Sand Filter

Q: Why is dirt passing through my sand filter?

A: A number of things could be causing the problem. It could mean that a lateral is cracked or broken, or a valve may need servicing. Or, air may be passing through the filter, causing a channeling effect that permits dirt to get by the filter. In the latter case, there may be nothing wrong with the filter.


Q: I have a 10 year old sand filter. How can I determine if the sand needs to be replaced?

A: The general recommendation is to backwash your filter when the pressure reaches 10 psi over the initial start up pressure. For example, if the start up pressure is 15psi, you should backwash when the pressure reaches 25psi. If the pressure does not return to the start up pressure after backwashing, it is time to change the sand.


Q: I have a sand filter and I'm getting a lot of sand in the bottom of my pool. Do you think there is something broken inside the filter, or do I have another problem?

A: If you are getting a lot of sand in the pool there may be a lateral broken in the bottom of the filter. If this is the case, the lateral(s) will have to be replaced.


Q: How can I find out how many pounds of sand I need to put in my sand filter?

A: Refer to your filter owners manual


Q: How do I change the sand in my top mount sand filter?

A: To replace the sand in your filter you must first disconnect the pipes going into the valve on top of the filter. Next, unscrew the complete valve counter-clockwise. Once the valve has been removed, you will be able to see the sand bed. The best way to remove the sand is to either use a portable vac or just dip it out with a small can. Once the old sand has been removed, fill the tank 2/3 full of water and just pour the new sand in. DO NOT get sand in the vertical pipe sticking up from the bottom of the filter tank.

Q: How do I Backwash my Sand Filter?

  • Turn off your swimming pool pump.
  • Turn your swimming pool filter multiport valve to the backwash position.
  • Open your backwash gate valve.
  • Turn your swimming pool pump on and run the pool pump for 2 minutes.
  • Turn swimming pool pump off.
  • Turn swimming pool filter multiport to the rinse position.
  • Turn swimming pool pump on and run it for 1 minute.
  • Turn swimming pool pump off.
  • Turn pool filter multiport valve to the backwash position.
  • Turn swimming pool pump on and run it for 2 minutes.
  • Turn pool pump off.
  • Turn filter multiport valve to rinse position.
  • Turn pool pump on and run it for 1 minute.
  • Turn swimming pool pump off.
  • Turn filter multiport valve to filter position.
  • Close filter backwash gate valve and turn pump on
  • Check swimming pool water level after backwashing - add more water if necessary.

Trouble Shooting your Swimming Pool Filter

My sand pool filter is running at high pressures.

  • Follow the backwashing instructions in your Owner's Manual. The sand bed may be clogged with mineral deposits that will not backwash away. Some calcium based chlorines and other alternative sanitizers will build up in your sand bed, and will require more frequent backwashing and changing of the sand.
  • Before you replace all the sand in your pool filter, try removing approximately 1" of the top layer of the sand, replace with the exact amount of sand you removed. Normal life span of the sand is about 4 - 5 years.
  • You may have to clean your swimming pool filter system with a special filter cleaner, check with your pool dealer for proper procedures.
  • Check to see if there is a closed or partially closed valve along your return piping, open the valve.
  • Your swimming pool pump may be too small to provide sufficient flow for proper backwashing. Your filter will function, but a lower design flow rate will cause your system to backwash improperly. Check the output of the pump to be sure that it equals your filter's design flow rate. Replace the pump if it is too small.


My pool sand filter is running in short cycles.
  • Improper backwashing could be the reason. Always backwash until the water runs clear in the valve's sight glass, usually about two minutes.
  • You may have have algae causing the pool filter to clog. By testing the swimming pool water balance with a test kit and super chlorinating, you should solve this problem.
  • NOTE: Some test kits may provide inaccurate results, we suggest taking a water sample to your pool dealer for evaluation. Be sure to take a water sample before shocking the pool.


There is sand at the bottom of the swimming pool.

  • The sand you are using could be too small, which will go through the filter system, then back into the pool. Remove the sand and replace it with the proper grade of sand - #20 Silica or 45-55mm pool sand, which can be found at your local pool dealer.
  • Your swimming pool pump may be too big for your filter. During backwashing the pressure can cause the sand to rise high enough to overflow into the standpipe, allowing sand to flow back into the pool. Refer to your Owner's Manual for the correct amount of sand for your filter.
  • There could be a loose lateral located at the bottom of your filter. Tighten any loose laterals, replace if broken.
  • Most calcium based chlorine, both powder or tablets, contain from 30 - 35% of what is called inert materials. This is calcium residue or dust, which many pool owners mistake for sand. You can confirm this by following these steps: During vacuuming, use a hand vac and pole. As the vac head approaches, , the sand will lay on the bottom, and will allow itself to be picked up. Most calcium residue will scatter away from the vac head as you try to pick it up.
  • If you have this problem, we recommend that you put extra water in yourswimming pool and vacuum to the waste line. If you vacuum to the filter, some of it will be trapped on the sand surface, allowing dust to get back into your pool.


My cartridge filter will not clear algae from the pool.

  • The three filter types will clear up algae, provided it is not in a live state. Consult your local pool dealer for the proper chemicals to help rid the algae. Most cartridge filter problems are caused by dirty, clogged or abused elements. Either clean the elements, or replace if torn or damaged.


My DE filter is running at high pressures and has a slow flow of water returning back to the pool.

  • The DE pool filter is loaded with too much debris or algae and needs backwashing or regeneration. If this problem persists and you notice the filter gauge pressure risingt from 7 - 10 psi above your beginning pressure, you need to regenerate your filter. Refer to your Owner's Guide for further instructions or consult your pool dealer for service.
  • Your swimming pool pump output might exceed the design flow rate of the pool filter. Make sure the pool pump is correctly sized for your filter.
  • If there is algae in the swimming pool, super chlorinate, backwash or bump/drain and recharge as needed. Make sure you are properly backwashing on your vertical grid filter. Refer to your Owner's Manuals for instructions.


My DE filter short cycles even after I backwash or regenerate and recharge.

  • The swimming pool filter elements may be clogged because of an accumulation of chemical deposits. Clogging is accelerated if chemicals are fed through the skimmer, operating your filter too long without DE after starting the pump, or operating the filter without DE. DE must be added as soon as the filter is full of water, and the pump is putting out a steady stream of water. Refer to your Owner's Guide for the amount of DE your filter requires.
  • Biguanide based sanitizers (i.e. Baquacil, SoftSwim) can cause short cycling.



My DE filter is leaking back into the pool

  • Be sure that the suspected material on the pool floor is actually DE. Pollen, chemical residue and plaster dust often look like DE.
  • You may have a tear in your filter elements, replace if necessary. Make sure that you assemble the internal parts properly!
  • Check for air leaks, as this will cause the system to leak DE back into the pool. If there are air leaks, install a check valve between the pump and the filter valve.


My DE filter has short cycles when vacuuming

This is normal if the swimming pool contains very dirty water. Backwash or regenerate and recharge more often. If there is a presence of live algae, add enough chlorine sanitizer to control this growth, then vacuum. The presence of alum or floccing agents will clog the filter. Vacuum so as to bypass the swimming pool filter. Do not use floccing agents with DE pool filters.


Will backwashing or regenerating my DE filter thoroughly clean my filter?

No, you must thoroughly clean the elements at least once a year. You can clean your filter elements using automatic dishwasher detergent. Remove the elements from the swimming pool filter, according to the instructions in your Owner's Guide, and hose them off with a forceful stream of water from your garden hose. Fill a large plastic container with the detergent, using about a 1/2 cup and warm water. Soak the elements for approximately 3 - 4 hours. After soaking, rinse off the elements again. Re-assemble your filter according to the instructions in your Owner's Guide. Note:do not soak elements in muriatic if the pool uses Biguanide products. This will damage the swimming pool filter.

You may choose to clean the elements with muriatic acid or other commercial pool filter element cleaners, mix according to the package instructions. Use extreme caution when handling any cleaning agents, as they can be harmful to the eyes, skin and clothing. After cleaning, thoroughly rinse all elements with cold water.


The swimming pool won't stay clear .

  • Your pool chemistry may be out of balance, allowing algae to multiply.
  • The flow rate through the filter may be low due to clogged or undersized piping. Cleaning the lines or changing to larger pipes will correct this problem.
  • Your filter operation time may not be long enough to compensate for heavy use or hot weather. Try running your filter for 24 hours to clear the water, then adjust to less running time.
  • Your pump may be hooked up to the wrong port on the multiport valve. If incorrectly installed, the filter will be flowing in reverse. Be sure the pump is connected to the port marked "pump" on the valve.
  • You could be backwashing too often. Backwash only when the pressure rises 7 - 10 psi over the starting pressure, or when the return flow back into the pool becomes low.


My swimming pool filter is noisy

An oversized pump may cause noise in your filter valve due to excessive flow. To test, hold your hand partially in front of any returns at the pool wall. If the noise subsides, this will confirm that the problem is excessive flow. It can be remedied by by installing smaller eyeball fittings in the return(s), changing the pump impeller size in the pump, or change to a 2-inch control valve.


My Vari-Flo valve leaks to waste

The valve seat gasket inside the valve has become worn or loose. You may choose to do this yourself or contact your local pool dealer for service. How do you replace the gasket? You will need a new gasket, obtained from your local dealer, some Krazy Glue, and a sharp 1/8-inch wide flat bladed screwdriver. NOTE: Mark the top and bottom of the valve with a marking pen. It's very important that you do not change the location of the cover when re-assembling. Remove the cover, usually six screws. Using the screwdriver, scrape out every last part of the gasket and cement, in order to get back to a clean flat surface. Put a fair amount of crazy glue on the flat side of the gasket. Place the gasket, flat side down, back into place - let dry for one hour minimum.


Q: My filter pressure gauge has dropped below normal for a clean filter?

A: If your filter pressure gauge indicates that pressure has dropped below the normal reading for a clean filter, check to see if you have a clogged pump or skimmer basket.


Pool Filters Data

Pool Filters Data 2

Changing the Sand

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This site was last updated 06/17/10