overanalyzer made some very valid points. I couldn't tell from the picture that you didn't have real rock in your tank. Yes, get some live rock and live sand. This is your biological filtration. Many HOB - Hang on back - filters provide mechanical and biological filtration. With the proper amount of live rock and sand, and a good HOB filter (I like biowheel filters, the wheel harbors bacteria that provide the biological filtration) you should have a good filtration system.
I also agree with going fish only for a while. However, keep in mind if you want to have coral in the future still that you need to selecet the right fish from the beginning. Don't get a fish that will eat all of your coral as soon as you put in. Some fish suggestions, IMO, for your size tank are:
6 Line Wrasse
Bicolor Blenny
Percula Clown
Long Nose Hawk
Pygmie Angel
These are just suggestions, don't do ALL of these. But pick 2 or three and do some research because some will do better with others.
I have a 20 gallon with a 6 Line Wrasse, Maroon and Gold Stripped Clown, and a Bicolor Blenny. That pretty much maxes me out on fish for my bioload.
I wish you luck and hope you don't give up.