Rick, met you over on another thread, it certainly sounds like an air leak on the suction side. If you bring a hose over to the filter pad and have it run a slow stream, you can direct the stream at any questionable connections or the valve itself (if your hose won't reach, you can use a bucket of water, slowly poured, to do the same thing). You used the words 'vari-flo' which indicates to me that you have a Hayward SP 733 valve (3 way). This would explain the problem - those valves are ^%#$&&$%&&$#$ !!!!. As I understand they have been or are being discontinued, they suck! (air mostly). If I'm right, you need SP 733Z1 for the replacement o-ring (if you can't get one, I can get it for you - in fact I have a couple in my basement, you don't mind that they've been through the laundry?)