eheim ecco 2234 making noises

[Bizz]

Every about 5 minutes my filters is making a weird rushing noise. it sounds like a pocket of air is flowing threw it. My airstone is about 5 inches from it and i don't see any air being sucked in. I've tried opening it up and starting it up again but the noise persistes, it only lasts between 3 and 15 seconds every time. I was just wondering if you guys had any sugestions to fix the noise. Thanks

Kyle

[Beardy]

maybe a little hole in the hose