Sand Filter « Pool and Spa 411

By: English & Le Page Pool & Spa  09-12-2011
Keywords: Pool

High pressure typically means that the filter sand is dirty and needs backwashing. Follow the instructions for backwashing “How do I backwash my filter?” or refer to your owners manual or follow the instructions noted on the label located on the tank body.
Check to ensure that no valves are closed in the return line to the pool and that there is no blockage in the return line.
Over time, the sand in your filter can become calcified or hardened from chemical buildup. If this has occurred, you can add a degreaser to try and loosen the sand. Often if this has occurred, the sand will need to be replaced. We recommend replacing the sand every 5-7 years depending on use.

Do I have to backwash daily? How do I know when to backwash?
No, you do not have to backwash daily. Excessive backwashing is not recommended. Over time, the effectiveness of the sand bed to remove particles improves.
Backwash the filter when the pressure increases 10 psi above the pressure when it was clean.
How do I backwash my filter?
Turn the pump off.
Turn the filter valve handle to Backwash. (Run out backwash hose if applies).
Turn the pump on.
Typically it will take 2-3 minutes to backwash the debris from your filter. If your filter has a backwash sight glass, backwash until the water is clear.
Turn the pump off.
Turn the filter valve handle to Rinse. (Note: this setting is not available on all valves. If you do not have a rinse position on your valve, set the handle to Filter and restart the pump.)
Turn the pump on and rinse for 20-30 seconds. This action removes any debris trapped in the filter during backwash.
Turn the pump off.
Turn the filter valve handle to Filter and restart the pump.

Why is sand going into my pool?
The most common cause is a cracked lateral in the underdrain system. You must remove the sand from
the filter and inspect the lateral / underdrain system and replace any cracked or damaged parts.

The sand you are using may be too small, allowing it to pass through the underdrain system.
The proper grade sand is #20 silica which is .45 to .55 mm in size. Consult with your local pool dealer. In some cases it has been common for algae to be mistaken for sand coming into the pool through the return jet. To be certain it is sand, a pile will form directly underneath the jet. If there is no pile accumulated it is most likely algae. Please refer to water balancing/Algae found on our service page, on how to combat algae or contact us at the office.

Why won’t my filter keep my pool clean?
You may not be running the pump long enough. Typically you should run the pump 8-12 hrs (min.) a day or until you turn the entire volume of your pool once a day. When a problem occurs it is best to have the pool circulating 24 hours to ensure enough filtration. Most pool pumps are designed to run continuously and are energy efficient. Check your chemical balance. Out of balance water can cause cloudiness. Make sure you have the proper amount of sand in your filter. Remove the dial valve and inspect the level of sand, the sand should be 1”-2” below the bottom of the basket. Also make sure the upper standpipe and lower standpipe are connected tightly into the basket. How old is the sand? The sand should be replaced every 5-7 years to ensure proper filtration.

I have algae in my pool and my filter isn’t clearing it up, Why?
Pool Filters can not filter out live algae. The algae must be killed by super chlorinating your pool water. Once this is done the dead algae can be removed with the assistance of a flocking agent.

When the dial valve is set on filter, water is leaking out the backwash line. Why?
A small amount of debris or sand may be trapped between the diverter gasket and the valve plate. To clean the valve, push down on the valve handle while the pump is running. This will flush out the valve and usually resolve the problem. Note that when you push down on the valve handle, water will pour out of the backwash port.
If flushing the valve out does not resolve the problem, then you will need to remove the valve cover and visually inspect the diverter gasket for debris or damage. Clean valve body and diverter gasket with water or replace diverter assembly if necessary. (Please keep in mind it is recommended to always turn the pump off when changing the filter head setting. Failing to do so will result in stretching and distorting the diverter gasket, causing a leak out the backwash line).

How often does the sand need to be changed?
As preventative maintenance, we recommend replacing the sand every 5-7 years.

How do I change the sand in my filter?
Turn off the pump. Set the dial valve handle to the test or closed position (If the system is below the water level of the pool be sure to plug the skimmer/returns if necessary). Remove the drain plug at the bottom of the tank and allow it to start draining, also remove the dial valve at the tank flange (the valve will be attached by hex head bolts or a stainless steel clamp). Remove the upper diverter and basket assembly. The easiest way to remove the sand is by using a wet/dry shop vac. (Note: Place a plastic trash bag in the shop vac canister for easy disposal.) If you do not have access to a shop vac, then you must scoop the sand out of the tank. If you scoop the sand, be careful not to damage the underdrain system when you reach the bottom of the tank. We do not recommend laying the tank on its side, as this could also damage the underdrain system. Once the sand is removed, inspect stem (center/stand pipe) and assembly (laterals) for any cracks, be sure to check the underside of the stem. If there is any hairline cracks or broken laterals now is the time to replace them. Cover the standpipe opening, you want to be sure no sand is poured into the stem. (Also cover the tank flange bolt holes, if applicable) Slowly pour the appropriate amount of sand into the tank. Remove the cover over the standpipe. Replace the diverter and basket assembly if applicable. Install the dial valve. If for any reason you are unable to replace the sand in your filter, E and L has trained and qualified service technicians that will be able to this for you. In most cases this service is approx 4 hours . Sometimes having a professional do this service saves you the time and aggravation if a problem occurs.

I have very little flow back to the pool, the filter pressure is low and water is coming out of the back wash line?
The hoses are connected to the filter valve incorrectly. The three connections on the valve are labeled: PUMP, RETURN, WASTE. Make sure the hose from the pump is connected to the port marked PUMP and that the hose to the pool is connected to the port marked RETURN.

There are several positions on the filter valve. What does each position do?

Filter- Water is distributed onto the sand bed. The water flows downward through the sand bed as dirt and debris are captured by the sand. The clean water enters into the distribution system at the bottom of the tank. This clean water is pushed up the center standpipe and returned back to the pool.
Backwash- Water is directed into the center standpipe and enters the distribution system at the bottom of the tank. The water flows upward through the sand bed washing the dirt and debris up and out of the filter through the waste line.
Rinse- Water is distributed onto the sand bed. The water flows downward through the sand bed to settle it after backwashing. The water enters the distribution system at the bottom of the tank and is pushed up the center standpipe and discharged out the waste line. (Note: This position is not found on all valves and is only used after backwashing.)
Whirlpool/Recirculate- Water flows directly through the valve and is returned back to the pool. This position is used if you do not want to circulate water into the sand bed.
Drain/Waste- Water flows directly through the valve and out the waste line. This position can also be used to vacuum heavy amounts of debris to waste.
Test- Water will not flow in or out of the valve. If pool equipment is below the water level, use this position when cleaning the hair and lint strainer on the pump. It will prevent water from flowing from the pool through the return line.
Winterize- This position lifts the diverter up from the valve plate to keep the diverter gasket from flattening out during off-season. It also allows air to enter the tank when draining.

Keywords: Pool

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