moving on up

[Magnus A]

I would say that the 400W versus 1000W talk is the wrong way to think.

There is three main factors in light.

1. color temperature, what wavelenght of the spectra do you cover. Nothing to do with Watt.

2. Light intensity at the leaf, lux or foot candela. Here you have an optimum depending on species! to much not good, bad growth, to little not good, bad growth. Watt has some to do with this. Bigger lamp gives longer distance and larger surface area with same light intensity. As light intensity is proportional against the squared distance you probably cover more area with the same intensity with 2*400 W than 1*1000 W.

3. heat, higher Watt produce more heat and therefore more problem with not burning your orchids. In the example above more heat from 1000 W than from 2*400W.