Ok so plumbing is almost done!! Can’t wait tbh. The far right is where I want to add uv has a gate valve that’s closed atm. That’s going to connect to the bottom of the 4 way. This is all going to be plumbed on to the under side where doors sit. It will be with a ball valve. So when I get ball valve on wall facing me looking at tank should I fill or finish the uv plumbing. Note tank has been with me for 4 years now want water in it!!!