Hello emmi_girl, I think you mean a terrarium not an atrium (unless you mean to use the fish tank as a skylight?) Not something I have done, but here are a couple of links with instructions: http://hgic.clemson.edu/factsheets/HGIC1457.htm http://www.ext.nodak.edu/extnews/askext/indoor/23.htm It will be important to choose plants that grow in the same conditions - it would be hard to grow cactus and moisture loving plants in the same terrarium for example. This sounds like a really fun project - a kind of microgarden, where you can create a whole little ecosystem. Good luck - keep us posted on how it grows. Maybe others who have created terrariums can tells about theirs and post images? I may try something like this myself to create a little cactus garden.
