Like all filters, the filters in your Gobi II Condensate Pump should be changed fairly regularly. During the season, your condensate pump is constantly in use. The filters pick up dirt particles and debris to keep it from getting it into you wall unit. Based on the environment in which your system is installed, filter replacement is typically recommended based on a visual inspection of the filter itself. For example, if you are in in environment such as a bakery where a lot of particles are present in the air, then your filters, not only in the condensate pump but in your wall unit as well, will need to be changed frequently. If your system is installed in a cleaner environment such as an office or home, the filter may need to be changed less frequently, perhaps yearly.