Suracefeeder: I encountered the same situation with my Zodiac Barracuda G3. High levels of Chlorine caused the diaphragm to become soft (according to the manufacturer). As it goes soft, it starts to move slower and slower until it just stays in one spot. I replaced the diaphragm ($30) and it's back to working great. I have a CYA of 80 with a pool temp around 88 degrees, so I need to keep the Chlorine at 10-15 ppm. I figure that I will need to replace the diaphragm once maybe twice a year.