I clean mine once every 2 weeks.
The suckers don't stick to the glass if they are getting old and rigid, and if the glass is dirty - that applies to all filters which attach with sucker. At least with Eheim filters we can get replacement suckers. I had one filter years ago where the suckers couldn't be removed so when they went rigid they couldn't be replaced.
The suckers don't stick to the glass if they are getting old and rigid, and if the glass is dirty - that applies to all filters which attach with sucker. At least with Eheim filters we can get replacement suckers. I had one filter years ago where the suckers couldn't be removed so when they went rigid they couldn't be replaced.