So I been running the newly installed filter and there are no detectable leaks in the plumbing I can see however after pump is off and then back on I noticed the water level in my SWG is down to almost half (note the SWG body sits at the highest level on the return side). When I turn the pump on it fills up but there are air bubbles coming out of my returns. Based on this I suspect the is a leak somewhere on my return lines or SWG fittings. Since I do not see any water leaks I am not sure how to find the air leak. Please advise on how to troubleshoot this problem.