Sep 19, 2012 #1 Rich440 Aquarium Advice Activist Joined Sep 14, 2012 Messages 142 Location Milford,OH Gould you change the filter in the sump once a month or wait longer?
Sep 19, 2012 #2 E EriksFish315 Aquarium Advice Addict Joined Jan 23, 2012 Messages 1,156 Location Syracuse If your talking about the filter sock you can change and rinse once it's covered in gunk.
Sep 19, 2012 #3 OP OP Rich440 Aquarium Advice Activist Joined Sep 14, 2012 Messages 142 Location Milford,OH Mine are just flat filters like you would see in an air conditioner It's an older sump
Sep 19, 2012 #4 E EriksFish315 Aquarium Advice Addict Joined Jan 23, 2012 Messages 1,156 Location Syracuse I would say change them when flow reduces or get noticeably dirty