I recently installed a new well storage tank in a house that I'm remodeling. Initially after installing the tank my pump would fill the tank with water then within several minutes the water had run back into the well and the pump was shortcycling on and off. I then pulled the pump out of the well and replaced the 200 feet of vertical pipe attached to the pump and installed a new check valve. This helped the problem a great deal however all of the pressure is lost now after an hour or two instead of within a few minutes as before. By the way, the pressure is lost between the storage tank and the pump somewhere because I have the water closed off from running into the house at the storage tank. The one thing that i did notice was that the o-ring in the pitless adapter appeared to be almost flat as if it was worn out. Would this be a possible reason for the pressure loss? Are the o-rings easily obtainable and replaced? thank you for any suggestions.