This is exciting and a great idea for a classroom!
Tank and sump looks great. If I could just make one suggestion from experience, put some support hangers on some of the pipe work if you haven’t already. Especially around valves you will be using as this is where stress will occur. Hangers near your bulk heads will also save stress from water weight or if you accidentally grab or put weight on the pipe.
Awesome build you have going. I’m following along.
I’ve been trying to find support hangers. Where do you get them for pvc?