Del..

I think you have a good amount of light, but I do see one problem. The plants under the 600w will receive quite a bit more light than those under the 400w. This will create a scenario in which you have bigger plants on one side of the room and an uneven plant canopy. Although, it is a good practice (imo) to rotate plants and spin the pots from time to time, this can be difficult depending on your setup. Also, keep this in mind...in the ladder stages of your plants life, moving them around could be risky. If you've done things right, some of the tops may be heavy and you could run the risk of broken branches if you weren't careful. So here's my advice...work with two of the same wattage lights in this particular setup. Preferably two 600w. 1200w in a 6x6 area will do nicely for you. You will be consistent from one side of the room to the other. and will make less work for yourself in terms of not having to rotate plants as much. Im here to help, holla back. Peace n luv

That only gives you just under 28 watts psf so it is a little low,but you can do it.

Yeah, 2 600s would be much simpler.

If you have to choose between either 1 600, or 600/400 combo... go with the combo.

As long as your vent and temps are ok, more light=better.

Just make sure that your setup allows you to adjust the lights easily.

Might be a good idea to also build a little "stage" for the plants under the 400 to start a little higher than those under the 6.

Ive done, == 600hps == 400mh == 600hps ==.

from a grams per watt sort of view, it wasnt the most efficient. But, it worked.