Is the threading on an Eheim BSP? I know that they're manufactured in Germany and the inlet and outlet threads are not NPT. If it is a European standard that is different from BSP then I can't remember what it is.
The practical relevence of this is, that I tried every way I could to put a 5/8" brass inlet on my Eheim 1250. I knew that the threading was not a perfectly exact match, so I used pipe tape, silicone sealant and an O-ring.
It leaked some initially, then settled down. I was just about to start installing components when it started leaking again. Time to drain, disassemble and fix at the source.
In a truly stubborn effort to use the brass fitting, I tried some pipe thread sealant. Any decent flow pressure and it would leak, too.
So out came the factory fitting, with a double circumference of PTFE tape, and guess what?. Been dry ever since (2 days now), so I can finally start assembling this system.
The moral? Don't try to mix pipe threadings! The difference in my case was very small, and should have worked with the tape and the silicone. But it didn't.
As a result I lost several days off this project, and bought a bunch of stuff that did me no good in the long run.
Sorry to rant, but I'd like to keep some other poor soul from doing this if I could....
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