I think somebody is mismatching watts and lumens on this one. A 400 watt HPS should cover 5 square feet surace area with enough lumens (measurement of light) to do a decent grow..or at least that what the man who sold it to me said. It has worked just fine so far. Assuming you have a normal heighth ceiling etc. If you have a ceiliing 3 foot tall you will burn it up. Course I told him I was raising Habaneros..sure he believed that one

Wink wink.