Quote Originally Posted by ellry99 View Post
Got strainer pump lid off with the mallet. Thanks!

Still cannot get prime running pump off main drain - I have 3 gate valves (main drain, pool skimmer, and spa skimmer) When I open the Ball Valve to the gate valves the pump loses prime immediately.

My pool guy says I have a leak somewhere and that he did not see any anti freeze from the pool close.

Any ideas where to go from here. ????
Happy to throw out a couple of half-baked ideas but I'm not the expert here.

A typical configuration would probably share suction between skimmer(s) and main drain (MD) and I assume that when both are open 50% this would not cause the pump to lose prime, and when you set suction at 100% skimmer or 100% spa there is likewise no issue. At 100% main drain, when the pump loses prime "immediately" do you observe a near total stoppage of water flow into the pump? Or is some water coming in? Do you see a lot of air bubbles and turbulence at this point?

Knowing the pressure reading (PSI) at the filter may help with the diagnosis or at least paint the larger picture. What is the reading at the pressure gauge --- normal and current PSI?

I've read enough about possible leaks to know that quite often a valve or a PVC connection or other fitting between the pump and the MD is faulty. I tend to lean toward surgery (replace the suspect valves between MD and pump, starting with those closest to the main drain); the approach is not especially clever but it may do the job. I wouldn't rule out an air leak at one of the valves, a distintegrated o-ring or 90 degree elbow that's come a bit loose, etc.

You could perform a bucket test to see if the main drain connection at the pool has been compromised - if the pool level is dropping that would indicate a water leak.

What else? An obstruction of some kind in the pipe. Might be able to reverse roto-rooter it back into the pool.

Worst case, you have some broken pipe connection beneath your deck or pool shell. Pick A) Employ leak detection company to pinpoint location and start digging; or B) Who needs a main drain, anyway?