I am stressed out about my return line. I had a pool service company come out to my house yesterday to open up my pool. My filter/pump has been running since around 4pm yesterday and this morning around 10am, I noticed that one of my return lines was still plugged. The guys forgot to uncap it. After I uncapped it, I noticed that a lot of bubbles are coming out of this line. I have three total and the other two have no bubbles. My first question is, are the bubbles the result of the line being capped for so long with the filter/pump running? Did that do damage somehow? My second question is, if the bubbles are totally unrelated to the cap, what might be causing this? I did not have this problem last year. If anyone could help and offer me some advice, I would greatly appreciate it. I am really worried!