Smite
Member
Are you thinking about using those flex PVC for the drain and return? I always thought about what would happen in an earthquake with all of these hard piping, and especially with external overflows. I know you have internal overflows, so that is safer.
I was thinking of doing a section of the drains and all of the return to the bulkhead. I like that movement will be absorbed but also they don't step down flow like a barbed fitting does. I would use that for sure on external for the exact reason you mentioned.