Just a heads up, Aqua UV come with 2” slip union bulkheads. You can buy the reducing bushing to your desired plumbing size, then It’s just a slip straight or 90 degree barbed fitting for connection to hoses.
I just picked up a Aqua UV 57w and am impressed with the build quality and design. It’s going to be easy to maintain with the unions. It can also be plumbed vertically or horizontally with unions facing up.
Cool idea on the flow rates if you can have it be automated with a dc pump and controller.