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Different Types of Pool Filters

There are three main different types of filters.

            Sand is the easiest type of filter to maintain. Sand filters can filter down to 40 microns. Trapped dirt builds up in the sand until the water flow is greatly restricted, and makes it difficult for the filter to do its job. Then, the system is backwashed, which clears out the trapped dirt and leaves the filter sand in place. The sand must be changed every 3 to 5 years depending on how much the filter is used and how dirty the sand gets. If sand begins returning to the pool, it normally means that the internals (laterals or hub) in the filter are cracked or broken and must be replaced.

            This filter is less maintenance than a D.E. filter, but the filters may need to be cleaned more often if there is an algae issue. This filter can filter down to 15 microns. It was originally made for spas and above ground pools, and is made out of a fiber material similar to paper. Cartridge filters do not have backwash valves, so they are just taken out and cleaned as needed. No backwashing is required for a cartridge filter, so you do not lose any water. Cartridge elements must be replaced every 1 to 5 years.

            D.E. requires more maintenance than a sand filter, but will filter up to a red blood cell. D.E. stands for diatomaceous earth, which is a filtering media (it is a chalky, fossilized material). Inside a D.E. filter there are filters called grids that are covered with cloth. There are seven full sided grids and one partial grid that make up the internal portion of the filter. The filter is set into operation, then a measured amount of D.E. is mixed into a slurry and poured into the skimmer, which then takes it into the filter. This powder actually works as the filter, as the grids just hold the powder into place. When the D.E. gets covered with dirt and debris, the filter pressure will build, and water flow will decrease. Then, the filter is backwashed (which removed the dirt, debris, and D.E.). your filter should be backwashed when the pressure is 8-10 psi over the starting pressure or once a month if the pressure does not reach that high. After backwashing, new D.E. must be added. Approximately every 6 months the filter should be disassembled and cleaned. If D.E. begins returning to the pool, it normally indicates that a torn filter grid or broken manifold may need to be replaced.

Backwash Valves
            Like mentioned above on the sand and D.E. filters, backwash valves are used to direct the flow of the water after it leaves the pump and before it reaches the filter. The pump must be turned off before changing the position of the backwash valve. The position the backwash valve is in determines where the pumped water will go. In the filter position, the water is sent through the filter in the opposite direction than when it is in the filter position. This cleans the debris out of the filter. The water and backwash debris then are sent out of the filter to the yard, storm sewer, etc. this water does not return to the pool.
There are two types of backwash valves that are standard on sand and D.E. filters:

Push/pull valve: This valve has two positions (up or down). Depending on which type of filter you have, the positions on the push/pull valve will differ. (ex. Down on a push/pull valve on a D.E. filter will filter, but on a sand filter it is opposite.) the positions will indicate either backwash or filter.

Dial or Multiport: This valve typically has six positions, which include filter, backwash, rinse, waste, recirculate, and close.
Note: Multiport valves for D.E. and sand filters are different and are not interchangeable.

– The information in this brochure is true and complete to the best of our knowledge, but without guarantee on the part of Central Jersey Pools, or on the part of any of its employees who disclaim all liability incurred with the use of this information.
Contact Central Jersey Pools at 732-462-5005

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