I'd try switching bulbs first. There's no way that a 400w MH should have a problem with a 2' x 3' area. If your bulb is really old, it may be running low efficiency and not putting out enough lumens. A decent 400w MH should be putting over 35,000 lumens. Since you've got six square feet of floor space, that's well over the 5000 lumens/sq. ft. standard.

Are you using an MH for flowering? I've never done that myself, but I've heard others say you get more stretch and less dense buds. If you've got a switchable ballast, you might want to try a CMH (Cermaic Metal Halide) bulb. They seem like the best "one bulb fits all" answer.
Roughrider Reviewed by Roughrider on . Too much light/heat? Hi guys. I am currently running a 400w MH in my 2'x3'x5' box with a vented hood and a fan pulling air out of the box/room. I am planning on buying a 600w HPS instead of the MH because the MH just isn't putting out enough light. My question is this: with 2 1/2 - 3 foot tall SOG flowering clones, is a 600w HPS going to be too much for my box? Is there such thing as too much light (lumens/square ft)? How much more heat will a 600w HPS produce than a 400w MH? Thanks! Rating: 5