New problem , I used my air compressor to blow out the 4 return lines. After I capped the last one then the main drains started bubbling. It seems that my two Jandy 3 way valves are not airtight because I was still seeing bubbles with all valves closed. Also after I removed the t-cell from the return line in front of the valve I could hear air leaking back. So I'll buy a couple of 2" caps to air lock the lines.