Bubbles from the return lines
My pool is finished and it is nearly perfect. But I have noticed that there are bubbles coming from the returns. Also, every morning that it starts it blows air from the lines for about 4 minutes causing a boiling effect due to the large volume of air in the system. My observation is this. It appears the bubbles are coming from the suction side line and not any seals or fittings on the pump. The return will shoot out bubbles off and on intermitantly as the pump runs. I am sure this is due to air building up in the filter and then being expelled. My pool builder is trying to convice me that there is no way that there is a suction side leak and that the bubbles are being caused by cavition. The suction side line is about 100 feet long. I have a 4x160 pump that runs at 1000rpm on the daily cycle speed. The plumber came over today and tried to talk me out of doing a suction side pressure test insisting that it was a waste of time. but I insisted. He will pressurize the suction side of the system on thurs. Am I being unreasable by insisting that there must be leak? Does anyones pool blast air out of the return after the system cycles on? Does anyone give any credibility to the cavitation idea? I would appreciate any guidance on this issue.