Ok, take out the hydrometer and replace it with a refractometer. They are actually accurate where hydrometers can screw you over with their inconsistencies. When starting a tank, you will need 1-1.5 lbs of live rock and 1 lbs of sand per gallon. This is where the bacteria will grow as you cycle your tank prior to adding livestock. It is a biological filter that will consume ammonia and nitrite, in the end producing nitrate.
Other than a master test kid, refractometer, salt, ro
water (this will prevent algae issues later on), and a large bucket for mixing water for water changes I wouldn't worry about anything else until you are cycled. During that time, you can figure out if you want to be a fish only or a reef tank. This will define everything else you will need for your setup.