I've had this house and pool for a couple years and am having a new problem. My pump won't hold its prime, I guess that is the way to say that. When it starts to fill up, it will get full but then flushes and starts all over. I am assuming air from somewhere, but where and how do I find it. I noticed the little glass bulb on the sand filter is also empty, would that have anything to do with it. Very frustrated and can't figure it out. Does anyone have any thoughts? I appreciate it.