I planted one in my 55, an in two weeks it went from about 10" tall, to the top of the tank and sideways over the top of the water to cover half the tank! I am low tech/low light and use T8 shoplight and no Co2...I did ask advise on trimming it and it seems it's easy enough to top it off where you want it to be.
I'm not sure if I like it or not.
I'm going to see if I can trim them, plant the trimings in other tanks, then keep the plants cut to a height I like. Think it'll work?