Im italian lol but i cant speak it well. Bulbi has this one covered. Take his answer and run with it! Having enough light is probably everyones biggest issue lol. We can never have too much. I also run a viparspectra but the 600W and I love that thing for its price. I have since moved on the bigger and better lights but I still use the Viparspectra alongside my other lights. 400W will get you a nice 4x4 cover and 600w will cover close to 5x5. Good luck my friend. https://growace.com/blog/how-many-grow-lights-do-your-plants-need/
hope that link helps out. It is the same info that Bulbi gave just with pictures and what not.