Well, thanks to some quick feedback,  I've added a couple items to my list
of things to pick up today.  I will go ahead and replace my plastic
couplings with some copper ones.  The reason I didn't do this immediately is
because I wasn't sure if the cooling solution would adversely react with
certain kinds of metal.

My suspicion now is that it will not.

I also will  be checking the pressure rating on the lines I installed.  The
one line I'm sure will be fine.  It's the flexible peice that I'm not sure
of.    What PSI rating should I ensure?

Thanks a ton!
Bradley Flubacher