What are the odds of a return line freezing and cracking?

[joeypools]

I own a small pool company in Massachusetts, and the past companies I have worked for only would put antifreeze in the skimmers, not the returns. If a pool has multiple returns, I always go back and forth individualizing each return until no water comes out and then plug it up. About halfway through my closing season this year I read a lot of people putting antifreeze in their return lines just in case. After I read that I started putting a half gallon of AF in each return using a flex funnel for extra insurance. I really started to freak myself out when reading more horror stories.

I've contemplated many times going back to those pools that I didn't put AF in the return lines and putting some in as the cost/annoyance of doing so would be worth the cost of fixing a repair under concrete, but I just wanted your opinions first. I'd assume the really only issue I could have is if I didn't notice a bad o-ring on the return plug which would allow water to leak into the line with no AF as backup. Let me know what you guys think. Thanks!!

 

[Pool_Medic]

What are you using to blow these lines? Cyclone or Big Blue? Are you blowing them until nothing comes out? What specific plugs are you using? Do you lower the water below the returns or are you using duck plugs?

 

[joeypools]

Always lower water below the returns, using a Cyclone 3HP, yes I blow them till nothing comes out (mainly worried about water getting trapped in low spots), and if its a threaded return I use the standard plugs with orings and if non-threaded I use whatever rubber twist expandable plugs fit best.