Gloria, the Haerella has been said to do better in a terrarium setup but mine is outdoors and does very well.
As long as you can supply the high humidity and mist it every day, a tank is not a necessity.
Susanne, I agree. Both plants are on the bottom shelf of my 3 teir plant shelf. They sit near my humidifier and the temp. stays around 70 and the humidity stays above 50% and more of course when I feed or water. I have a Dend. cuthbersonii x Dend. goldschmidtianum that is sitting above the humidifier and it has two big buds that will probably be opening this week.