Well I wouldn't think the FBF would put enough additional pressure on the
pump, as any obstruction in the output would be equivalent to turning the
output valve to the off position while the pump is on. BTW I guess you
could test this by doing just that: disconnect the FBF and turn the valve
off and see if it leaks more.

On the otherhand, there is the more likely scenario that you need a new
O-ring. If I recall, Hagen no longer makes the fluval 404 anymore, and
you may have an old model. The rubbery-ness of the seal tends to go with
age.

Or, what has happened to you has happened to me on my fluval, after six
years of dependable operation, it sprung an invisible crack within power-
head unit. How, why? I don't know. Unfortunately, I had to retire the
unit.

good luck

"CanadianCray" wrote in
:

It is leaking from the seam where the large "O"ring is?

Thanks