Try this:
Take it all apart and put petroleum jelly (Vaseline) on all the O-rings. Look for them on the fittings where the hoses are connected as well as the larger ones where parts of the filter come together. Put a dab on all the hoses as you put them back on the fittings. It will make them slide on easier. Add a hose clamp. (There are plastic ones available in aquarium supply or maybe plumbing supply, or look for Marine Grade stainless steel)
If the petroleum jelly on the O-rings works it means the O-rings are starting to get old, perhaps stiff, perhaps crack. Time to order new ones. I regularly apply petroleum jelly to the rings of all the filters. As the O-rings are in use they start to deform and reshape to match the groove where they sit. When I reassemble the filter the O-rings are not always placed exactly where they were, and that minor reshaping that has happened can be just enough to cause a leak as the O-rings get old.
Most basically, the air is entering on the intake side, not the outlet side, so look for leaks there. Is there a hairline crack in the tubing or the fitting that arches over into the tank? While you have the filter partially disassembled run some water through the intake tubing and fittings and see if you can see any water coming out. (Do this over a bucket, or even better, outside- it can get messy)
Are you running an air bubbler near enough that the Eheim is inhaling some bubbles?
Take it all apart and put petroleum jelly (Vaseline) on all the O-rings. Look for them on the fittings where the hoses are connected as well as the larger ones where parts of the filter come together. Put a dab on all the hoses as you put them back on the fittings. It will make them slide on easier. Add a hose clamp. (There are plastic ones available in aquarium supply or maybe plumbing supply, or look for Marine Grade stainless steel)
If the petroleum jelly on the O-rings works it means the O-rings are starting to get old, perhaps stiff, perhaps crack. Time to order new ones. I regularly apply petroleum jelly to the rings of all the filters. As the O-rings are in use they start to deform and reshape to match the groove where they sit. When I reassemble the filter the O-rings are not always placed exactly where they were, and that minor reshaping that has happened can be just enough to cause a leak as the O-rings get old.
Most basically, the air is entering on the intake side, not the outlet side, so look for leaks there. Is there a hairline crack in the tubing or the fitting that arches over into the tank? While you have the filter partially disassembled run some water through the intake tubing and fittings and see if you can see any water coming out. (Do this over a bucket, or even better, outside- it can get messy)
Are you running an air bubbler near enough that the Eheim is inhaling some bubbles?
