Suction cups

[Nain]

I have an ongoing problem with the suction cups that hold the discharge spray bar in place for my Eheim filters. Over time the cups harden and lose their grip. What causes this? Is there any way to rejuvenate the hard cups, or do I just keep replacing them?

 

[Mike Wise]

These plastic suction cups just naturally harden under water over time. I don't know of any way to rejuvenate them, but you could silicone them to the side of the tank. I wonder if one could make silicone suction cups? They should hold up to being submerged.