Dean’s RO lines are a game changer. The concept saved me hours and the final product definitely feels more polished and flexible.
I think your missing this piece, you’ll need to use these (https://www.amazon.com/dp/B00YYKB9K2/ref=cm_sw_r_cp_api_glt_fabc_DEQ6X71E1EVGQY8GGRMC ) to split your lines by shelf on the rack and then build manifold runs across the racks, each tee dropping a line to each tank. I used the Ziss air valve to end each of my lines in the tank.
Are your tanks all the same size? I have a similar system set up and I have each valve feeding similar sized tanks. (i.e. one for the 10s, one for the 20s and so on) This way I can feel pretty confident that each tanks water change over is fairly consistent. If you run a line to a rack with mixed volumes your larger tanks will get a smaller % water change per minute of flow than the others.
Check out Greg Sage’s water change system videos. He maps out his system in detail. Steve Poland Aquatics also has a great video on the topic. I up with a hybrid of a few different systems that fit my needs.
Pump wise I was able to find a 1/3hp sump pump on eBay cheap. It’s got the power, but it is very loud (especially in a plastic bucket). My rack is in the basement and I can hear the pump kick on through the floors. I didn’t consider this when planning and it’s the only regret I have with the setup.