I changed my sand at the beginning of this year, I'm not sure it has anything to do with it but here goes. When I hook up my auto cleaner it will run fine for about ten minutes with strong suction, and a strong flow from the return. After about ten minutes the cleaner will lose sution and just sit there. When I pull the cleaner out of the return there is little suction in the skimmer, and very little flow from the return. If I backwash the filter it will return to full power. When I backwash there is little to no dirt in the sight glass. When I changed the sand I was very careful to make sure I added the correct amount of sand and throughly cleaned and inspected the laterals to make sure none was broken. I'm not sure what is happening. Any ideas?