Wow!...Looks like a really fun, intense, and significant project. Keep us posted on the progress.
It’s hard to tell from the pictures but it’s actually pretty well supported. That is just a water change drain line that’s connected to a 1.5” SCH 80 bulkhead and also strapped at multiple points on the bottom of the shelf. And, at the terminal point, it’s also bulkheaded to the concrete slab.