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Leaking Eheim Filter

6445 Views 35 Replies 10 Participants Last post by  NZ1001

I bought a second hand 90 gal tank with a Eheim filter (about 8 years old). I was super excited, but the dang thing won't stop leaking. We've redone the seals with vasoline, and the main gasket is still soft, but the side, below the handles keep filling with water. Any help would be appreciated. The Cichlids are already in the tank, so long filtration breaks are not a good idea. Please help!

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I would start with a new o-ring first. Have seen many O-rings that look fine or practically new, but all it takes is one imperfection in the right spot to form a leak. Also that would be a cheap first thing to try. Just double check that there is no hairline cracks and that the canister is not warped maybe by taking some measurement across the opening in several different spots and comparing. Hope this helps.
Thanks for th e response. I don't quite know what the O-ring is. I have the book calling the two rings in the trays the rubber seals, and the large rubber seal at the top is the rubber gasket. Is one of these the O-ring?
Yeah sorry that is what I meant. The main seal that seals the motor to the canister itself.
Thanks I am trying again to clean the sealing ring/gasket
Sometimes something as simple as moving the O-ring around so that a particular part fits in another spot will get you some temporary relief. Sometimes there are super small defects in the ring or the groove where it fits that we can't see or feel. Moving the ring puts two different things together and sometimes it works but it also is time to replace it as usually it is only a temporary fix for a seal that is drying out too much. Eight years on using a rubber part is not bad at all, though.
In the future don't use vasoline. It will actually destroy rubber o-rings. Go to a swimming pool store and get some of their pool equipment lubricant. I bought a tube of "Magic Lube" and it is teflon based.
Amusrobs, which model Eheim filter do you have? If it is the Pro II series, the problem may be the priming pump o-ring. If you need the owners' manual, check their website here ... st=afilter

Dotbomb, Eheim recommends regular Vaseline as an alternative lube for all their gaskets/o-rings when you run out of Eheim lube. This info is found on their website under FAQ.

I have seen frequent posts about Vaseline deteriorating rubber o-rings. As consumers, we don't know if the seals, o-rings and gaskets on aquarium equipment are truly made of rubber. More than likely they are a combination product. When in doubt, contact the manufacturer of your particular aquarium product via phone, email or in the FAQ section of their website.
Deeda said:
Amusrobs, which model Eheim filter do you have? If it is the Pro II series, the problem may be the priming pump o-ring. If you need the owners' manual, check their website here ... st=afilter
+1 - have had two do this - the key is the OP stating the water is under the handle area. Fairly straightforward fix, but does involve getting deep into the guts of the filter. Search around for leaking eheim pro II...

That o-ring is tough to find, but hopefully you can get it working again with just the vaseline.

Good luck, and let us know how it works out for you.

Thanks to all. We've tryed all the "at home" fixes, and it's leaking like mad. I put the filter in a tupperware bin, and now the heater fritzed. I woke up and the water was down to 25 degrees. the poor fish have been through the ringer. we've lost one already. We lifted the filter and put it on a pot so it won't sit in water. I thik I'm going to have to replace the whole thing.

the model is the pro II series. Nothing in the manual is called an "O ring", so I'm getting mighly confused. Sorry, I'm a beginer. We have "rubber seals" that run through the trays, and the "rubber gasket" that is in the top lid.

So if anyone knows about the heater, and which one the o-ring is, let me know. Thanks again for all your help
Amusrobs, the pro II series has a priming button on the top of the canister that is pushed to initially prime the filter with water. There is an o-ring that seals this primer to prevent water from leaking out like you have seen first hand. This o-ring seal is not seen in the owners manual.

If you are comfortable with taking the filter head (the top of the filter) apart, this o-ring can be replaced. There are a couple places online where it can be purchased. Here is a link to some good instructions for fixing the filter once you purchase a new o-ring. Link is here

I have fixed my filter using these instructions and it no longer leaks. I bought by o-ring at & it can also be purchased at These are the only 2 places I have ever seen it for sale.
Go to if you need to replace the O ring in the priming button on top. This is usually a slow leak from the top. If it is leaking on the side, then you have to replace the gasket. You can purchase replacement ones at most online stores.

The O ring is not meant to be replaced by the consumer, but it can be done. The gaskets need to be replaced every 5 years or so.
ok that is much more clear now! It must be leaking from the primer button, because the entire head of the filter fills with water. I have to turn it all directions to drain the lid when I take if off. It must have dried out while it sat for two weeks with no water. I wonder if it can be saves, or if I should just buys a new one.

Thanks so much for all the help. The knowledge you can get on this site is amazing!
Here is the link for replacing the O ring -

Let me know how it works out. I have an extra Professional II that I took out of service for the same reason.

It is absolutely worht digging into the top of the filter and simply adding vaseline to the o ring around the pump. Both of my Eheims were leaking and a new coat of vaseline fixed the leak. I have purchased an extra, just in case, but so far I have not needed to use it.

You are on the right path now.
We got it all pulled apart, thanks for all the information!! Sure enough there is a small tear in the o-ring. I'm going to order one now from atomic.

Thanks for all your responses!
Glad you were able to get it apart and find the bad o-ring. Keep us posted on getting it fixed. Be sure you follow the instructions on re-assembling the primer pump. I pinched the new o-ring my first time & had to take it apart a second time. I didn't tear the new o-ring so there wasn't any problems.

BTW, I did buy a couple spare o-rings for future use or in case I damaged the new one. I'll probably never use them but you never know.
I've opened the motor, and sure enough the 0-ring has a tear in it. It must have dryed out and when we went to prime it again the o-ring was being pinched and tore.The people at atomicrice have been so helpful. The new o-ring is on the way.
Amy, be sure to use a nice thin coat of lubrication on the new o-ring and on the the cavity where the primer pump/o-ring assembles. I have used the Eheim grease (which only seems to come with a new filter), regular Vaseline, plumber's silicone grease (a bit too tacky) and the spray Eheim lube (works great).

I actually never use the push to prime button anymore. When performing just the regular filter maintenance, the valves keep the water primed in the hoses so there is no need to use the primer button.

If I am also cleaning the hoses of grunge or algae, I just pre-fill the intake hose about half way with water before installing the hoses back on the tank. Once connected back to the filter, open the valve assembly and the filter should start filling back up with water without having to use the primer button.

I think this will help with not having to replace that o-ring again. If you really want to use the primer button to prime the filter, I would recommend buying the Eheim spray lube as it is really easy to reach that darn o-ring.
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I don't recommend vaseline as it is petroleum based.
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