magnum 350 not working

[fishcurse]

i just bought a 125gal tank that came with a magnum 350 pump/filter that is also looped in with a coralife uv sterilizer. well i can hear the pump running and ive got all the hose switches open but it doesnt seem to be moving any water. i have no idea how to mess with this or change the filters or anything. its on the other side of tank from the sump so i think they were using it for extra filtration and to have good water movement cause i believe these things are only up to 100 gal tanks. i dont know please help

 

[weberian]

You can find the parts diagrams and user manuals on the web. The PDF manual will show you how it goes together so you can take it apart and look for an obstruction or you may have to clean the impeller shaft if it's got calcium build-up.

 

[reefforbrains]

Sometimes you need to fill it with water to prime the system.
Also check for closed valves on the intake or return line.