If you have a tube full of water and there is a leak in the tube below the
tank water level, it will drain until the water level is at the same
height as the leak point. Having had a Fluval 404 for years and now an
Eheim I can say that I *never* had a leak in either. With the Fluval I had
to be very careful about seating the main O-ring but once seated, no
problems.

If you are uncomfortable with this, then a sump pump with siphon break is
probably a better choice. Or, maybe you can get reverse flow siphon breaks
to put in line on your Fluval hoses.

--
- Mark -

Hi Mark,

I'll check into the reverse flow siphon breaks. I've also been told
that you can drill a hole in the intake hose just below the water line
to break the siphon if a leak should occur and you begin to lose water
volume. Any thoughts on that? Thanks again.

Grant