Came across this while browsing and thought of this thread ..A little diaphragm-operated pressure switch at $1:50
hook it up to a relay to kick your power off ...If your pump stops or you lose pressure in your system ..
Dont know if it would work but at a $1:50 its somthing to play with lol
Oops help if i post the link
http://www.allelectronics.com/cgi-bi...-10&type=store