Swimming pool sand filters are one of the ways to keep your pool crystal clear and clean. This type of product uses sand as a means to collect and remove debris from a body of water. Sand is contained in a vessel or tank, water is pumped into the top of the tank, and into the internal distributor. This allows the pool water to "rain down" and flow through the media. As the water flows through, dirt and debris are collected and removed from the water. The debris is held behind and the clean water is returned to the swimming pool.
What are some of the items found and associated with a type of filter?
1. Multi Port Valve OR Control Valve
What are some of the functions found on a standard Multi Port Valve?
o FILTER - For normal filtering and vacuuming.
o BACKWASH - For cleaning the filter bed of accumulated debris.
o RINSE - Use after completing the backwash cycle to ensure all dirty water is rinsed from the tank to waste.
o WASTE - By-passes the tank for draining or lowering the pool water level and for vacuuming heavy debris directly to the waste line.
o RECIRCULATE - Water is recirculated through the valve by-passing the filter.
o CLOSED - Shuts off the flow from the pump to the filter
Internal Parts
2. Tank Or Vessel - Main body of the unit.
3. Top Diffuser - Allows the pool water to enter the tank and distribute the water inside the tank.
4. Media - Captures the dirt and debris from the pool water as it flows through.
5. Laterals - Located under the media, allows the pool water to exit the tank and flow back to the pool.
How are sand filters cleaned?
Most filters come equipped with a valve, commonly referred to as a Multi Port Valve. The Multi Port Valve has various settings allowing water flow to be directed in many direct directions. One of the directions is BACKWASH. In the backwash mode the water inside the tank is made to flow in reverse. Instead of the water flowing from the top of the tank down, the water from the pool is fed into the bottom of the tank through the laterals. This causes the sand to be churned, the dirt and debris which has been contained is flushed out of the tank through a separate waste line. Many Multi Port Valves have a sight glass for viewing this process. As the water is backwashed, use the sight glass to inspect the water, as the water becomes visually clean the backwash should be considered finished, the pump stopped and the valve now put in the RINSE mode. Reenergizing the pump in the rinse mode allows the water to flow in the standard operating direction and allows settling to occur in the tank. Dirty Water is flushed out to waste during this process.
NOTE: This process will lower the water level of the pool. Once the pool level is lowered additional chemicals may be needed. Retesting of the water will be required to determine the type and amount of chemicals which will be required.
What if backwashing is not enough?
If backwashing does not "clean" the media, the time has come to disassemble the unit, empty the tank and replace the sand. The media will deteriorate over a period of time, become hard and crusty, and forming channels. When this takes place, backwashing will not be enough to allow proper filtration. It is important to remember the following when performing this task.
1. If the filter has not been disassembled for some time, when removing the multi port valve, top dome or top half of the tank, remember to have new o-rings available which will be in the area of disassembly. Old o-rings stretch and crack over a period of time and need to be replaced periodically.
2. Carefully remove the old media from the tank. This can be accomplished by scooping or by using a sand vac tool (a tool which by using a garden hose and exhaust hose, vacuums the sand out of the filter tank.
3. Inspect the bottom laterals, checking for damage or cracks. Replace any laterals which are defective to prevent by-passing of sand back to the swimming pool.
4. Prepare to refill the tank with the new media (Check the instruction manual for the filter and use the size and type which is recommended).
5. Fill the tank half full with clean water
6. Slowly and carefully add the new media to the tank. Use caution not to damage the laterals during this process. Add the correct amount for the size filter being serviced.
7. Reassemble all parts removed, top half, dome, and valve, replace o-rings as required.
8. Position the multi port valve in the RINSE position to settle the new media, check for leaks, once settled, turn off pump and return the valve setting to the filter position. Restart Pool Pump and begin normal operation.
How often does the sand need to be changed?
Filter size, pool usage, bather load and weather conditions will dictate the time frame for changing and recharging the filter.
These types of filters have been utilized for many years as an effective means of swimming pool water filtration. Maintaining the filter and valve will provide many years of service, keeping your water crystal clear, enjoyable and ready for fun.