Someone else was looking to make a 3-D background for their tank. My preference on this is to hide the filter equipment with plants, aquatic wood, and rocks. As poetic irony suggested, amazon sword is easy to grow, and in my 100 gallon tank I have one that's 2 feet tall and hides all the equipment on one side. I've periodicallty thinned the older leaves too and I still get a nice background. My reasoning is that if you can use natural materials why not?

The other posts say much of what I'll say. If you have an aquarium store in your area they should have most of the easy plants to grow that don't require much light. Anubias nana (small Anubias), Anubias Barteri (large), Java moss and Java fern and Amazon Sword are all easy low light requiring plants. The java moss and fern need to be tied to aquarium wood with thread or rubber bands. I suggest all these because you don't need to buy an expensive high output light to grow them, you can use a double fluorescent shop light with plant bulbs turned on 8-10 hour a day, and you'll have less problems with algae. I don't know much about 3-D backgrounds. I prefer to put a dark blue back-drop taped to the back of the tank and fill the back of the tank with larger plants and aquarium wood. Amazon sword grows very large and fast so this is good for that. Sometimes you can have problems with roots clogging up an under-gravel filter but I've always used one anyway. I use a mix of plant growing substraight and regular aquarium rocks to grow them in, but most of these plants will grow in anything.(remember: the Java moss and fern need the wood) Sometimes Java fern will die when you buy it, but small leaves will grow out of the dying leaf. I just then tie the new leaves down and I haven't had any further problems with this kind. You don't need an under gravel filter if you have another that is big enough. I always over filter myself. If you do use the UG filter note that very small substraight particles can clog it up. Good luck. Plants are fun! PS I guess I forgot that I already replied to this post. I'll leave what I just wrote. I have nothing better to do right now. ;)