Clean your swimming pools' filter cartridge when the PSI
reaches 8-10 PSI above its initial reading when you first put in a new or clean
filter cartridge.
For spas or hot tubs, establish a regular cleaning routine
based on the usage.
1) Remove
the cartridge filter from the filter's housing following the manufacturer's
instructions.
2) Use a garden hose to with a straight flow nozzle to
wash down the filter cartridge. Work from the top down,
cleaning both the inside and outside. Hold the angle of the spray at a 45
degree angle for best results. Clean in between all the pleats.
3) Rinse and repeat until all the dirt & debris is
gone. 
4) If the filter cartridge is still dirty or has
been used in a spa or swimming pool where oils like perspiration, sun tanning
lotions/oils are frequently used, then soak the filter cartridge or at least one
hour (overnight is more effective) in either A: a commercial filter
cleaner, or B: in a solution of one cup of Trisodium Phosphate (TSP) to
five gallons of water. or C: a solution of one cup of dishwashing liquid
to five gallons of water.
5) Rinse the filter cartridge again, repeat 2-4 again if
needed.
6) If the filter cartridge has a coating of Algae,
calcium carbonate (residue from calcium hypochlorite), iron or any other
minerals, soak the filter cartridge in a solution of one part muriatic acid to
twenty parts water until the bubbling stops. WARNING: Failure
to remove all oils and cleaning solutions from steps 2-5 above could result in
the permanent restriction of water flow through your cartridge filter resulting
in a partial or complete failure of your cartridge filter.
7) Rinse the cartridge filter completely and replace it
within the filter's housing as per manufacturer's instructions.
NOTE: We do not recommend using Diatomaceous Earth
(DE) powder with any filter cartridge. The powder particles will
become trapped in the body and will shorten its life expectancy greatly.