This is an excellent overview of brines and salting. Just made some feta yesterday, which obviously uses a nice salty brine. It was a good reminder about the whey-brine having a more easily balanced pH. I made mine out of water before I thought about it, and I'm going to have to check the pH...
Just be sure to use one of those pipe bender tools, especially if the copper is thin. It's so easy to put a kink in the pipe. It looks like a good price on tubing, and I would jump on that price! Good luck to you.