I have a Oceanic Bio-cube 29A, i have a clown fish, a white ennenamy, and a small white crab. I'm not that knowlegeable about salt water tanks but this one has been up for a while. but the ennenamy stays closed, he opened up a couple days ago but closed back up, I'm not sure if its cause the salt level is low or too high, or if theres not enough oxygen being admited, the tank does have this egg shaped ball thing that looks like a fan maybe, but does not work,, and the tank evaporates pretty rapidly, then air comes out of the tubes for filtration, is that supposed to be where it comes from, please if you can give me some advice or tips it would be appriciated, i dont want these fish to get sick, my son would be sad, oh and it has long algea or sea weed growing in a couple spots?