I'll be building a Koi pond this spring. I'm aiming to do a quality build with quality materials. One of the first things I need to get in place in the bottom drain plumbing. Most of what I've read says to use schedule 80 PVC, but that's not something I'll find at the local HomeDepot or Lowes. Is that something I'll likely find at a local plumbing supply store? Would I need to order it online?