How to take care of an elodea plant in a tank of water?

Use aquarium gravel in a 3-10gal. tank. You don't need chlorine tablets just let the water sit over night. You shouldn't need to change water more than 20% a month, just keep it topped up. Plant about half in the gravel and half on top. They like lots of light so try to put them in a sunny window. You could even add a couple of goldfish. Elodea give little oxygen bubbles you can see and the fish love oxygen. If you don't get fish, you will need to add fertilizer made for aquarium plants. Once you get the hang of it you can add many other plants to your collection. RScott