Yea, i know that to not kill the fish it will be months before i can even buy them and put them in. I am fine with that, cause i still need to save up to get fish i want.
Not months.. for fish.. but a few weeks maybe.
Does your tank have holes drilled in it? Can you post a picture of the tank? It matters as forum members help you, more than you think at the moment.
Ditch the blue balls.. they are nothing but problems. They cause several kinds of ecological problems the inventors never dreamed of.. and may be why the person you got the tank from got out of the hobby.
The thing with the blue balls in it is the sump... it is good you have that.
If you photographed everything but the tank you do have a few missing things.
You need a heater, a way to measure temperature, a way to measure salt content of the water .. we call that salinity... and most likely you will need a skimmer... I hope you have a skimmer.
We need to know if you do or do not plan to have coral.. if not you can get by much cheaper. .. Being able to have coral in that sized tank requires deep pockets at first.... mine is a 90 gallon and I have about $5K+ in the set-up, and I too bought a used "got everything" rig for a bargain price. I want you do go in with your eyes wide open. For example: to have coral you will need at minimum one pound of live rock for every gallon of water, while the expense of live rock can be done in some cost saving ways, live rock runs about $7 a pound.
You said you have something you think is the reef, can you post a photo of what that is??? .. it may be what was live rock...
You will need a salt water aquarium water quality test kit. If I were in your shoes I'd want to be able to test for pH, nitrates, nitrites, ammonia, KH (hardness or alkalinity), PO4 (phosphates), temperature, and salinity.
My best suggestion for now is to spread out EVERYTHING and photograph and post pictures of EVERYTHING.... no matter how unimportant you think it may be.
Do you know if the previous owner still has other tanks up and running? I am wondering if they are still in the hobby or dropped out for some reason.
You have come to the right place!!!! This forum can get your there....