Gonna stock my 125G with Oscars and other big guys. Just filled it with fresh city water... haven't even decided on media for my Fluval FX5, let alone turned it on. I'm not in a big hurry to load it with fish. So what do I need to do to get the water ready for my stock? I'm a big fan of natural rather than running out to purchase chemicals just so I can speed things up. New at this so baby steps please. Not even sure what to use to test the water. I'd appreciate a step by step guide on what to do now and how to make sure the water is ready for live stock.