return pump nocking

[erikjphillips]

My return pump which is about a week old is being difficult. When i do a water change, i shut the pump down so i can change the water and not have the sump level drop too low. now, when i turn it back on its making a nocking sound. when i take the return line off of the pump, it doesnt push any water. The LFS i bought it from says that the line needs to be primed. i dont think thats the case if its not pushing water without the line on it. any suggestions?

 

[mcarroll]

Hm...can you post a pic of the installation and tell us what kind of pump it is?

It's true that some (most) pumps are not self priming, and it is possible that a knocking sound would be a result of "running dry" so to speak. Something that's is very, very not-recommended to do to one's pump.

Let us see what you're dealing with though and post a pic. At the least, what pump is it and describe how it is installed.

Have you taken the pump apart to examine the impeller assembly?

-Matt

 

[REEFKEEPER10]

Sounds like a air bubble is trapped in it.