I have a 125g brackish tank with Columbian Sharks, Archer fish, Silver Needlenose Gar, a Freshwater Flounder and blue legged hermit crabs. What exactly should my sg be? I've been told everything from 1.015 - 1.025 - this is a broad range... Can someone help narrow it down a bit? Or is anywhere in this range ok? This is my first brackish setup and I don't want to cause harm to anything. Thanks!