I have a 14 year old pool with a hayward super pump and a triton tr-60 sand filter. Pump was new last year with new attachments (impeller etc.) up to the basket housing. I run the filter about 10 hours at night on a timer. I noticed a few weeks ago that the pump was running dry. I do not know how long it ran like that but it could have been a few days. I reprimed it and ran it. I noticed the filter was "sweating water" on the outside of the casing. When I wiped it off, water immediately seeped out. I figured this may also let air in when the filter is shut off so I bought a new triton tr-60 sand filter because the specs on the new one matched the old one and I figured it would match up to the existing plumbing. Well the fittings on the new one were approx 1 inch higher so I had to cut the pipes where necessary to raise the plumbing 1 inch to attach the new filter. I primed the pump and everything ran fine. When I shut the pump off I could hear the filter immediately start to drain water. If I restart the pump within a couple of minutes the pump will prime but there is already alot of air that needs to be bled out of the valve on top of the filter. If I restart is after a couple of minutes the pump has already lost its prime. I have checked for air leaks at all the normal places, I have tried the shaving cream trick on all fittings. I have changed the seals on the backwash valve, jandy valve and pump basket lid. I have looked for water leaks when turning system on and off and listened for any air leaks. When I prime the pump it immediately sucks the water out of the basket housing and when primed it runs at 12 psi. Filter system will run with no problems, no bubbles in pool until I turn it off. Right now I run the system for 2 days straight and turn it off for 2 days, reprime and run again for 2 days etc. I have not been able to get a good explaination on how this system prevents the water from draining out and losing prime when shut off. I need some troubleshooting help if possible to prevent just changing major parts until its fixed. I cannot see any wet spots on the ground that might indicate any inground plumbing leaks. I would appreciate any help or advice that can be offered on how to proceed. I have attached pictures to show the system I have. Photo 154 shows the original plumbing and the problem I had with the new filter install. Photo 170 shows the new filter installed with the modified plumping, photo 165 shows the pool itself for reference. Thanks in advance for any help.