As long as the water level isn't too low the extension tube wouldn't matter for it not working. The ext. tube may be a good idea once you get it working though if you feel the tube is not deep enough. You said you primed it so thats out, unless you didn't fill the entire filter with water. You should only need to add enough to cover the impeller but I noticed that if you fill the filter up it starts up quicker. Is it churning? Or can you here the pump motor running? If not plug a lamop into the outlet to make sure it works and/or it is not a switched outlet that may be off. Check to see that the impeller is seated properly. Check to make sure the flow adjust (if it has one) is not turned down. Hope this helped.

Hi Jenny,

Make sure that the slits in the intake tube are covered with water.....It sounds like it might be sucking air...and therefore won't move the water....stop the filter in your 10 gallon and take the extention off and place it on this one....and see if it works......if it does thats the problem.

A couple other things that come to mind...make sure that the intake tube is down tight in the filter. And is the filter sitting level? This may cause the filter to also suck air instead of water.

Did you take some water out of your 10 gallon to start the cycle up faster in your new 20 gallon.

Good luck!
Sierra

I'm having the same problem the tube if it goes in the filter box slot the filter will not work, if I pull it out of the slot it woks but with quite a bit of noise and you can't put the lid on. Tetra replaced the filter but the new one won't work either. Everything was set up according to directions the filter do work on a 10 gal tank. I did notice the filter box when hung on the tank wall will not set all of the way down on the 20 gal tank. I think I will solve the problem by going back to a 10 gal tank. Any suggestions?

use some home made suggestions for this problem