Hi I'm from New Brunswick....... My neighbor used to run a 600 gallon Cold water system. It run very well for years,as he was a Scuba Instructor. All he used to keep the water cold,was use the unit out of a freezer. For water changes,every time we went diving we would bring about a 50 gallons of Bay of Fundy water back with us. He used to keep Wolf Els,Lobsters, Star fish Hermit Crabs Flounder fish,and lots of other goodies from our great Bay of Fundy here out east. When the animals got to big for the tank we released them,and caught new ones. It was too easy
Good Luck,as i'm sure u will enjoy it just as much as a tropical SW setup.
Marcel