Cooling beer lines, moisture and mildew?

I'm working on my keg setup, with the fridge in my basement and my taps in my kitchen. I want to insulate the beer lines, and use copper tubing and a pond pump to keep them cold. I will have three beer lines, and two copper tubes.
I have some thick insulation that is meant for copper pipe, and it fits perfectly inside 2 inch PVC. If I put the beer lines and cooling lines inside the insulation, then put that inside PVC, will I have moisture and mildew problems? Or will there not be condenstion, since the copper lines aren't exposed to open air?

Would I be better off putting the lines inside a smaller piece of PVC, and putting the insulation outside of that? That would let any moisture drain out, but it seems like the insulation would be more effective right up against the lines.

What if I did it the first way, but used plastic for the cooling lines instead of copper? I know it isn't as good of a temperature conductor, but I wouldn't have condendation.

So what do you guys think? What will keep the beer in the lines the coolest without causing problems? Thanks!

You will only get condensation if you get air movement. Just be sure to seal it up well so there is no air movement and you will be fine.