There are 3 basic types of pool filters:
1) Diatomaceous Earth (D.E.)
Diatomaceous Earth Filter: By far the most efficient filter for swimming pools in both energy efficiency and filtration capability. DE filters will filter out particles down to 3 microns in diameter. You cannot see a particle with the naked eye until it is around 40 microns. DE filters should be taken apart, disassembled, cleaned and inspected for damage twice a year. This is crucial for the proper operation of your DE filter. Once filter is clean and running the clean pressure should be noted and written down for future reference, as it is an important number. Backwashing is a procedure that needs to be done once the filter pressure reaches 7-10psi above the clean pressure or every other month.
***Click here for Backwashing instructions*** All DE filters require that you add DE powder back to them anytime they are cleaned or backwashed. You do this by adding one scoop at a time of DE powder to the skimmer while the pump is running. This is an extremely important step because the filter will not work without this powder; it is this powder that actually filters the water. Costly internal damage will occur by running a DE filter without any DE powder.
How much powder you add is also very important and is determined by the size of the filter. The most common sizes are: 24sq-ft | 36sq-ft | 48sq-ft | 60sq-ft | 72sq-ft
There should be a label on the outside of the filter that lets you know the size. Its best to buy a proper DE measuring scoop from a pool store to measure the DE powder. A 32oz drink cup from a convenient store will also work as a perfect scoop. After complete disassemble and cleaning add this amount. 24sq-ft - 5 scoops 36sq-ft - 7 scoops 48sq-ft - 9 scoops 60sq-ft - 12 scoops 72sq-ft - 14 scoops
After you perform a backwash subtract two scoops from your original amount and that's how much DE powder you will add. It is very important to add these amounts as any less or more can cause internal damage to the filter.
Cartridge Filter: A cartridge filter is the second most effective type of pool filter. They will filter out particles down to 10-12 microns in diameter. These filters need to be taken apart at least twice per year or when pressure reaches 7-10 psi above clean pressure. It's a very simple process of taking out the paper cartridges and hosing them down with a water hose.
Sand Filter: Sand filters are the least efficient in filtration and in energy efficiency. Sand filters filter out particles down to around 30 microns in diameter. Sand filters should only be backwashed when pressure reaches 7-10 psi above clean pressure.