A blue light?
It depends on what type of tank you want to have, if it is FO
, or reef. As for chemicals...you shouldn't really need much, if at all. Depends on what you want your tank to be. You should pick up an API master test kit so you can keep track of the levels in your tank. You should also decide if you are going to mix your own or buy saltwater pre mixed. And realy, thats just the start.