Pentair Clean & Clear cartridge filters contain these black end cap inserts on both sides of the cartridge (top,bottom).
When these cartridges are cleaned, is it necessary to remove these 2 end caps?
Also read for the first time this blurb from the owners manual:
When the cartridge element filter is used on new pools and after cleaning the elements, introduce into the system .5 pounds
of diatomaceous earth per every 100 square feet of filter area, (a one-pound coffee can equals .5 pounds of diatomaceous
earth). Mix the diatomite with water and pour it into the skimmer after the pump is primed and the system is operating. This
will enhance the filtration of your water.