I bought a Zodiac G4 today and the guy I got it from showed me it in his pool and it worked fine.. jumping back a half inch or so each time it pumped. I bring it home throw it in my pool and it is sitting there pumping and seems to be working fine but it is not moving anywhere, just sitting in same spot pumping itself. I've emptied out the pump basket and recently back flushed the filter and added DE. I don't know if you can change the pressure of your system and maybe mines not pumping hard enough? The gauge right above my DE filter tank reads about 18-20 once it's up and running a couple minutes. Any pointers?