I’ll have to lay on the floor, thank god there’s rug lolAPI copper tests work, but they are VERY difficult to read. If you know the exact water volume of the tubs, then you can dose to that, and then test it to get some idea as to what a "normal" test result looks like.
I'm really leery of people setting up treatment tubs on the fly; you'll lose sideways viewing of the fish and that's vital in regards to being able to see the fish eat, how fast it is breathing, how the disease is progressing, etc. As mentioned, ammonia control is also very difficult in a new tub(s). Don't use Prime for ammonia control, Amquel is a better choice. Better still would be to use Amquel AND some "bacteria in a bottle".