I am hoping there is someone that can help me...
We just opened our pool for the season and I can get both pumps (one for the filtration and the other runs the slide and deck jets) to suck from the skimmers - but when introducing the main drain - it looses it's prime. If I run the pump just on the main drain it will gain suction and then loose it quickly - just a constant
pattern. I can tell that there is air somehow getting into the system. Any ideas?
We have also sensed a leak all winter...are these 2 things connected?
My pool has 2 skimmers, 2 main drains at 6 feet, and is a vinyl lined pool with a salt system.

 

you either have a busted pipe or possibly a valve sucking air. If loosing water it the bust is below the water line.

 

you have a suction side leak between the pump and the main drain. you can examine the pipes that are outside and run water over any exposed part of the pipe. If it resolves a problem - you located your leak, if not, it's probably underground.

if you pool loses water, it might very well be this leak. when pump is running, the leak will result in air being sucked into the system making your pump lose its prime. when pump is off the leak will be water coming out of the pipe.