it's an algae, therefore it does need light. some people have their lights on 24/7 while others have the lights when when the main display tank light is off. but overall, it really doesn't matter as it needs very basic light to thrive.
never tested how long they can last without light but i wouldn't try as it risks fouling up the entire water in the tank.
it will grow regardless of the nutrient level, but then again no tank is too clean to the point where there's not even a trace of nutrient.