Leaking hose help

Hi All,

First and foremost thank you for taking the time to read this. We purchased a home a few years with a 28' AG pool. I've learned a lot about how everything works but the previous owner seemingly glued the hose setup together. In the video you can see that it's leaking out the top of the screw ring. The obvious solution would just be to unscrew it and replace the o-ring or whatever is leaking in there. I can't unscrew it any more than it's moving in the video. I tried using two channel locks and it just won't budge.

Can anyone tell me what my options are here? I don't know if the connections are correct in the first place.

Leaky Hose Video

Thank you!

Update: I was able to re-tighten the union with the help of my neighbor and a strap wrench he had in combination with channel locks. I'm leak free thanks you you guys. You saved the day!