Imagine if you could have a huge tank, like 150 gallon and you divided it into two and on one side you had a saltwater aquarium and on the other side a freshwater, i think that would be amazing to show the difference in fish behaviour and colouration. i think if i had a tank like that i could just sit and watch for days like a movie marathon.
My dream tanks are about 5-6 1000 gallon tanks. I have a list of them and really want to know if it is compatable. But to add onto your idea, I would have 2 150 gallon tanks and have them right beside each other.
Tom