All pool filters including a cartridge filter get dirty, block water flow and increase pressure inside the filter. When the filter pressure reaches a certain point you must clear it. A filter with a high pressure reading that is ignored can cause permanent damage to the pool filter. Each filter has a maximum point for pressure build up.
A cartridge filter is easy to maintain. The system consists of a filter that houses a pleated filter that looks similar to an automobile air filter. The filter is wrapped around a PVC core with a polyester material that is meant to be durable yet porous enough for water to circulate through it. The cartridge slides into a base at the bottom of the filter.
You should consider the pressure gauge the lifeblood of your filter's maintenance system. The pressure gauge is at the top of the filter and can indicate to a user when it's time to clean the pool filter. The normal operating pressure will range based on pool capacity and filter size. You should note the normal pressure reading when you first install the filter or after each time you clean it.
When the normal pressure reading on the gauge is 8 to 10 lbs. per square inch (psi) above its normal reading, it's time to clean the filter. For example if the normal reading is 15 psi then the maximum pressure you should let your filter reach is 25 psi.
Cleaning The Filter
You have to remove the cartridge when the gauge indicates it's time to clean. Turn the filter off and turn the air release valve to remove the pressure form the filter. Twist open the top portion of the filter to expose the cartridge. Remove the cartridge and hose it off with moderate pressure to remove dirt and small particles of debris. Once the filter is free of dirt and debris, place it back into the housing. Reapply the top of the filter and tighten the air release valve.
Once Per Month
The pressure gauge will tell you when the filter is dirty. However, pool professionals believe that the cartridge filter needs cleaning every three to four weeks. Do not clean the cartridge more than you have to. Every time you clean the filter it becomes less effective. Eventually you will have to change the filter, under proper maintenance routine, every four to five years. However, it does not hurt the filter system to change the cartridge and replace it with a new one as often as you would like. The newer the filter cartridge is the better the unit will work.