[untamed]

re: Ball valve directing flow to refugium...

I'm thinking that a ball valve will work fine for that application. It will be a bit crude to adjust the flow into the refugium, but once you get it set you'll be fine if you just leave it alone. You'll then be able to fine tune the water exiting the refugium with a gate valve.

As the Herbies don't allow any air into the lines, you can always have the pipes exit silently below water line. That also avoids splashing and bubbling which results in less salt creep everywhere.