You did not list any of your test equipment or I missed it. Your water quality will dictate where you need to concentrate your efforts as your tank becomes populated. Then you can decide whether you need/want more equipment. Water quality is key such as alk, calc, salinity, ph etc depending on what you plan to keep. Water changes may keep them correct. Depending on how you populate your tank that may not be enough. Research any and all fish and/or invertebrates you want by visiting stores and websites. Find out what their needs are so you can better anticipate where you are headed. When you know where you are going your path will become clearer. While plans always change with time at least you will have a starting place based on knowledge.

