Don't mean to offend you, but I'm going to be brutally honest. Those filters you have are junk.
Admittedly, they're pretty typical of what stores sell for pond filters, but then again your problem is pretty typical of many other backyard ponders who have similar filters. The proper solution is to look into larger scale, home made, external mechanical filtration concepts that are easier to service and clean, and chuck those junky, tiny submerged filters in the garbage, or if you want to have the fountain, just remove the media and just run it as a fountain pump.
I know, you've already spent the money on those filter/pump thingys and you don't want to spend more money (and time) buying more pumps and filter making material. That's understandable, however if you don't you'll likely end up going down the same path many backyard ponders before you end up going, and that is returning to the same store where you bought those crappy filters and buying a bunch of pond "clearing" chemicals and gimics like barley straw.
Admittedly, they're pretty typical of what stores sell for pond filters, but then again your problem is pretty typical of many other backyard ponders who have similar filters. The proper solution is to look into larger scale, home made, external mechanical filtration concepts that are easier to service and clean, and chuck those junky, tiny submerged filters in the garbage, or if you want to have the fountain, just remove the media and just run it as a fountain pump.
I know, you've already spent the money on those filter/pump thingys and you don't want to spend more money (and time) buying more pumps and filter making material. That's understandable, however if you don't you'll likely end up going down the same path many backyard ponders before you end up going, and that is returning to the same store where you bought those crappy filters and buying a bunch of pond "clearing" chemicals and gimics like barley straw.