Filter FAQ’s

How often should I clean my DE filter Grids?

Most filter manufacturers recommend cleaning the grids at least once per year. This will normally be done at the end of the season when closing down the pool or at the beginning of the season once the pool is opened. Filter grids should also be checked for damage and replaced as needed during the cleaning process. Refer to your filter manual for information on changing grids.

How often should I change the sand in my filter?

When the filter is backwashed normally and correctly the sand should last 3-5 years. Refer to your filter manual for specific recommendations for your filter.

How do I change the sand in my filter?

The process will vary by filter manufacturer, you should always refer to the documentation for your specific filter. For most filters you will first turn the system off then follow the steps below for your type of filter. NEVER USE PLAY SAND, you must always use sand made for use in filters to avoid damage to your filter or pool.

For most top mount filters, you must first disconnect the pipes leading into the valve and open the drain plug on the filter. Next, remove the clamp holding the multiport valve to the tank body. 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 wet/dry vacuum or just scoop it out with a small can. Once the old sand has been removed, hose out the inside of the tank to clean the filter out. Once this water is drained, replace the drain cap and fill the tank 2/3 full of water. This is to protect the lateral assembly while the new sand is added. Add the sand slowly till the laterals are fully covered, then just pour in the remaining sand. DO NOT get sand in the vertical pipe sticking up from the bottom of the filter tank. The standpipe may be covered with a paper cup to prevent sand going into the pipe.

For a side mount tank, rotate the multi-port valve to the closed position and open the filter’s drain plug. Remove the tank closure dome and expose the top diffuser. The top diffuser lifts off and the old sand can be removed. The best way to remove the sand is to either use a portable wet/dry vacuum or just scoop it out with a small can. Once the old sand has been removed, hose out the inside of the tank to clean the filter out. Once this water is drained, replace the drain cap and fill the tank 2/3 full of water. This is to protect the lateral assembly while the new sand is added. Add the sand slowly till the laterals are fully covered, then just pour in the remaining sand. DO NOT get sand in the internal piping.

When and how do I correctly backwash my filter?

You should always refer to the documentation for your specific filter. However for most all filters you should backwash when the pressure reaches 8-10 psi over the clean starting pressure. If you notice that your pressure is high or the water is not circulating in the pool it needs to be backwashed. To backwash most filters you will first turn the system off, then turn the valve handle to backwash. Turn the system on for approximately 2 minutes or until the water runs clear in the sight glass, then turn the system off. Rotate the valve handle to rinse and turn the system on for approximately 1 minute then turn the system off. Rotate the valve handle to filter and turn the system on.

Why does the pressure go back up even after I backwash?

The most common reason is that you are not backwashing properly, refer to your filter’s manual or the instructions above to properly backwash. This can also happen when the filter is clogged with algae, your filter can not kill algae. You will need to purchase an algae killer to clear the pool and after many backwashings the pressures will stay down. There are other causes listed below based on which filter you may have.

DE FILTERS

You are not putting the proper amount of DE powder back into the system each time you backwash. Most filters have a label which indicates how much DE should be used. Refer to your filter’s documentation. Purchase a DE scoop to ensure proper measurment.
The filter needs to be broken down and cleaned then recharged with the correct amount of DE powder.
Verify that the pressure gauge is working properly by turning the system off and checking that the pressure goes to zero. If the pressure does not go to zero, replace the gauge.

SAND FILTERS

Verify that you are backwashing properly. If you were not follow the steps above to properly backwash and see if the pressure will stay down.
Your sand may be clogged due to age or certain chemical use. Try using a filter aid or cleaner to help the sand and remove any build up.
Verify that the pressure gauge is working properly by turning the system off and checking that the pressure goes to zero. If the pressure does not go to zero, replace the gauge.
The sand could need to be changed due to age. If the sand is less than 3 years old you may try removing the top 1″ of sand and replacing with new sand of the same amount first. If this process does not work replace the sand.
Verify that there is not a closed or partially closed valve on the return line.

Why does sand go into my pool or out the backwash line?

A lateral could be cracked or broken, the multiport valve may need servicing, or air may be passing through the filter, causing a channeling effect, which permits dirt to get by the filter.

You could be using sand that is too small, allowing it to pass through the laterals back into the pool. Verify that you purchased sand meant for use in a sand filter.

Why does the multiport leak out the backwash line?

The valve seat gasket inside the multiport may be worn or loose. You will need to replace it. Some multiports require that you replace the Refer to your manufacturer’s documentation. Contact Lusk Pools for assistance.