So as the title says, my 8 year old daughter wants a Nemo. She will turn 9 in August. For her birthday, I thought to set up a saltwater tank with a clown or two. The only problem is....I HAVE NO CLUE ABOUT SALT WATER AQUARIUMS!!!! So I need to know, in baby steps, what I need to have and do. I have an empty 20 gallon long that I could use for this. Hopefully that is sufficient as it fits perfectly on her desk while still allowing her to do her homework. It has it's standard hood and light. I have available: a Fluval 105, 2 TopFin 10 HOB, an Aqua Clear 402 powerhead, and Stealth heaters 50w-250w that could be used for this if they are appropriate. With what I have now, what do I need and in what order? Would anything else be able to go in the tank?