2x400w or 1x600w switcable hps

been using one 400w for three years now and i am looking to upgrade a bit, my room is 4x4x4 i am thinking a new 600w with a switchable ballast so in the summer i could turn it down a bit or two 400w and just turn one off in summer can anyone tell me what one will give me better results in density and yield all comments welcome.

Hi,

600 watt HPS setups are the most efficient, giving more lumens per watt than the others. Also, a 600 watt HPS will give you almost 6000 lumens per square foot for a 4x4 surface. This is plenty, and you won't need to go much higher unless you are enriching with CO2. Two 400 watt setups will give you 6900 lumens per square foot for the same surface, but cost you an extra 35% in electricity. I'd go for the 600 watt switchable ballast.

Here's some information on grow lighting if you're interested.