Really brackish organisms are more versitle versions of their freshwater and saltwater cousins. Really brackish systems open more doors to fishkeepers. My favorite thing about brackish is excellent biological filtration. In freshwater there are really only bactieria in your filter. With brackish water you can incorporate sponges and cnidarians into your filtration. I have 2 hang on the back filters on each of my tanks. One is hooked up to a refugium I made myself out of a kriter keeper. My filters are heavily modified. I might make a tutorial in the DIY Hardware section, until then I am keeping under wraps.