I tend to agree with PA reef. A 1.8 gallon micro-nano would be cool as hell, but very difficult, and you would very likely not be able to keep any fish in it at all. Perhaps a shrimp, and a mushroom or two, thats about it. Now if you hook it up to a 10 gal or bigger refugium, it will still be a difficult tank to keep up with, but easier than a 1.8 with a half gallon refugium. I know your money is tight, but you can get a 10 gallon aquarium at wal-mart for about 9 buck, with no lid or stand of course. Most of the expense isn't in the tank though, which is a good thing. That ten can hold 20 pounds of sand, give or take, and 12 pounds of live rock, definitely a plus.