You are only cleaning it to prevent clogging and to remove an outer layer of bacterial growth form time to time. Also, be sure to clean out the intake vents. The filter itself requires little or no long term maintenance other than to check for brittle plastic. You may want to clean out the lift tube and the filter housing from time to time for cosmetic reasons. Dirty airstones can be refurbished by cleaning with an algae scrub pad and a soaking in a strong bleach solution.
Check valves .
Depending on the quality of your check valves, you may wish to replace them every year or so. Air Pumps . Inexpensive air pumps may be replaced periodically, or if you have an aptitude for working with small machine parts, you may consider replacing flappers and diaphragms as needed. The cheaper quality airline will harden with age and may become brittle. Check the airline periodically for signs of deterioration.