I think BRS carries some but I hunted them down from different places. I think they were originally called click clamps.Wow, great setup!
Where did you get those grey pipe hangers/clamps?
https://www.bulkreefsupply.com/sm-clamp-for-pvc-pipe.html
These are the basic clamps. They have accessories like threaded nipples and metal threaded tabs that fit into the bottom slot. I used those to make a double sided clamp.