What cycles in a tank is not the water. It is the sand, rock, ect you put in the tank. When I set up my qt, I use water from a large water change out of my tank. Add fresh water to and a powerhead or 2 to get the proper salinity. Add fish. Qt tanks can be made out of anything. Those large tubs from Walmart, a brute trash can ect work good. Pylon a filter on it & do regular water changes. I think sometimes we make things in this hobby more difficult than it really has to be. And our fish are way tuffer than way give them credit. I know I do the same.