Join Date: Jul 2010
Location: Outside Philadelphia, PA
You may wish to consult the book Dynamic Aquaria by Adey and Loveland. See if your local library can get it for you, rather than buy it, since the book is fairly expensive.
Chapter 23 is devoted to setting up a model ecosystem of Chesapeake Bay. In this system one end is FW and it progresses through various sections when the other sections having more and more salt in them, until the final section is Full SW.
To keep the salinity correct in each section, computer controlled gates were used to allow water flow between adjacent sections. If the salinity was too low, the gate to the more salty water was opened. If too high the gate to the less salty water was opened. The full strength SW section used an RO unit to remove pure FW from the SW. This maintained the salinity. The FW went back to the other end of the system.
Obviously this was a huge project, and beyond your typical home aquarium, but you might get some ideas of what could be done, if you want to get involved in all the equipment to control it. A 2 or 3 tank version would be a great project for the right person.