Currently we have a 10 gal and 20 gal freshwater aquarium tanks. I would like to start a salt aquarium (possibly 40 gal) but understand it is very expensive. I talked to a guy at a LFS, and he said that the only difference between salt and fresh is that there is salt in the water. He told me if I was using fake plants etc, I only needed to worry about the salt/water mix and that I could by it from him for $5/gal. Is that too much money for salt water? How do I find out the right combination of salt and water to maintain a 40 gal tank? I don't plan on reef tank for awhile because I am told those are really hard to maintain. I would just like some feed back on the best way to start a salt water aquaruim and if the information I mentioned above is true. Appreciate everyone's time and comments. Thanks.