I currently have a new Eheim Classic 2217 and have a problem just after the shut off valve on the inlet side where the hose is dripping even after tightening the hose clamping nut as tight as I can do by hand. Any ideas how to solve. See photo.
You might consider cutting an inch or two off the hose, running the newly cut end of hose under really hot water, then while it's still warm and soft attach it to the double tap valve again and clamp it down. This should give you a better seal.