How much light for 2.5Mx1.5M?

Currently, I've been using a single 1000w, but I'm worried about yeild.

I've been told that 2x 600w would be a lot better, but I don't see how that makes sense, since it's just 200w more.

If I had another 600w to the 1000w for a total of 1600w.. will that be enough?

Thanks!

Trackr .first off you're underpowered . For every sqft of your space you want a minimum of 40 watts . So yes throw that 600 in there and watch your girls grow