A quick update....I'm still crawling along.
I have the tank moved into its final position, squared and leveled. It's a tight fit behind the tank due to the shutters and those huge 2" return lines, but I made it work. I jumped in the tank and took a picture looking down behind the tank showing you the dual overflows and center return line. The perpendicular pipe you see is the 2" return running from the left side of the tank (where the UVs are) to the two returns on the right side of the tank.
I have two things left before I can do a leak test. First, I need to get the pumps glued to their respective bulkheads inside the return section of the sump (using unions w/barbed fittings and silicon tubing) and plumb the dual check valves to the bulkheads on top of the sump to exit the stand towards the UVs.
After that, I will run the 2" return lines out the left side of the stand to two 2" flow sensors before entering the bottom of the UVs. Water will exit the top of the UV's into 2" Hayward true union ball valves before connecting to the runs that are behind the tank.
You'll notice I have 1/2" side-outs where the plumbing enters the bottom of the UV. I will add 1/2" Hayward ball valves to these side-outs so I can bleed all the water out of the UV body should I need to do any large maintenance on the UV. Since I have 2" ball valves on the exit of each of the UV's, I can shutdown one UV and return pump without affecting the other return path and most importantly no floods.
Getting the UVs perfectly aligned with the return lines isn't an easy task since the UVs aren't attached to the stand and the walls aren't completely square. I hope to have all my measurements confirmed today so I can cut all that pipe for a dry fit.
You should also notice a fresh water supply line in front of the bottom of the UVs that will eventually be plumbed all the way to the right side of the tank for the skimmer auto-clean and RODI system. I'll temporarily plumb some 1/2" PVC that will dump directly into the to the top of the display for the leak test. Once I'm done with the leak test, I'll tear that out and connect it to the 1/2" line that is running behind the stand. Unions are AWESOME!
Lastly, the 1.5" PVC that is running behind the return lines is my drain/waste line that goes outside to the city sewage. I have a full 1.5" pipe going behind the stand to the right side of the tank so I have access to a waste drain for my skimmer auto-clean and RODI waste water. On the left side of the tank, I have two wye's installed on the sewage line. The first wye provides me easy access to dump-out water changes and to connect the Neptune Trident waste line to. The second wye is connected to a clean-out trap just in case I get a clog. Plumbing all of that is a low priority since it isn't a prerequisite for the leak test.
Well, that's it for today.