I have a bio cube 29 gallon freshwater aquarium with live plants. Its dimentions are 20"L x 20.75"W x 19.25"H with two 36 watt fluorescent 16" lights. I have had it for a while now, and the jungle vals that I got a while ago are spreading like crazy and this other plant i have is also spreading over the aquarium. They are growing around other plants and crowding them. Originally i only had three jungle vals on the left side but now there are more all over the aquarium. How do I stop them from spreading any more? Another question I have is what are some good background plants that wouldn't be too big for my aquarium but would take up a large space in the back corner?