I want to start a 40g brackish tank.I have a lid, filter, heater, undergravel filters, lots of fake plants, gravel, and a big cave.How much marine salt do I need?I think all I need to get is marine salt and hydrometer because I already have Ph probe.What do I need and how much money are we talking?I live in sacramento, were around here can I get brackish fish like dragon gobies, silver monos, spotted/figure 8 puffers, scats, ect???I know sand is better than gravel but can I just use gravel?I don't want to get them online because shipping cost more than the fish. Thanks for your help.P.S. what fish in this list can go brackish?Peacock eel, kuhli loach, dino bichir, rainbow fish.