Thanks to any in advance for the help with the following
We bought our house in 2012 with a pool in the back. Its an 8k gallon vinyl lined in-ground pool, 3/4 hp pump with a clean & clear cartridge filter. Unfortunately, the genius that designed it placed the pump & filter effectively one story above the water level, as well as a good 50-60 feet away. In finding all the tricks, I can finally figure out how to get it primed with some efficiency (and thanks to some plumbing changes).
Here's my problem. Starting last summer, the pump has begun to lose its prime whenever it is not running. Within a few hours of shutting off the pump, it will become completely deprimed, forcing me to have to manually reprime the pump. This causes us to not be able to keep the pump on a timer, its either on 24/7 or not at all.
We had two separate pool repair firms out last year, neither able to find any kind of leak around the machinery, but also unable to diagnose why/how it would lose its prime. One did redo some plumbing for me (finding the original installation of a backflow valve was done completely incorrectly, aka upside down as well as being a vertically valve put in a horizontal line, put in a water fill line at the pump to help give it water as well as a sliding valve to shut for when I change the basket) and helped setup for an easier prime. However this year the problem persists. Manually prime, run, have to shut off.
This year however, I'm afraid its developed into a worse issue, probably pointing to bad lines. On Saturday, we ran the pump & heater. Prior to bed, I had the pump shut off with the waterline at approximately the mid-point of the skimmer inlet . Ambient temperature during the day in the 70's, at night, 50's. By the next morning, the water level had dropped to below skimmer bottom, pointing towards 3-4 inches of waterloss in under 16 hours.
Any thoughts or suggestions are greatly appreciated. I'm hoping there is a simple solution, however, I'm afraid of it becoming something much more.