Magnum H250 filter won't stay primed.

[Buddha's Ghost]

I have a Magnum H.O.T. 250 that I've been running for awhile now with no problems.
Last week it stopped pulling in water from the aquarium.
I hadn't touched it for a couple of weeks prior to it stopping.
The filter is clean. When I initially fill it with water and install it, it will pump the water out that's in it, but won't draw up fresh water from the aquarium.
The intake tube from the aquarium is unobstructed.
I purchased a new impellor, but this solved nothing.

If anyone has some good advice I'd really appreciate it.


thanks in advance. :)

[AngelMom]

I know nothing about this filter, but a quick search of the Marineland site yielded this in their FAQ (http://www.marineland.com/cus_faq.asp):
Q: Why does my H.O.T. Magnum expel water and fill with air?

A: The D-Ring Cover Seal may be missing, out of place or damaged. To ensure a tight seal, it should be placed in the channel located on the underside of the lid. A small amount of silicone grease will also help to make it air-tight.

Also, always make sure you fill the canister completely before starting the unit.

Make sure the Center Exhaust Tube is positioned correctly in the bottom plate. If it is crooked, it will put undue pressure on the lid.