Thanks for the reply. Yes, I have checked the multiport valve and there doesn't seem to be any problems there. I have it set to waste so that the (sand) filter is taken out of the equation. And there is plenty of water in the pool...it has all the signs of an air leak but I've repiped everything and don't see any water leakage or hear any air leakage when I shut off the pump. I'm really stumped. thx..