These lights are over rated by the manufacturer, so 400w might only be 200 actual watts,, but it depends on the manufacture. The really cheap ones are not going to give you the power you need for a good yield. Even if you are actually getting 200 w, you are still under powered for that size tent. A 200w light would be ok for a 2x2 tent, but if you have a 4x4 tent the light would be 1/4 as powerful as it would be in the 2x2. These lights have a certain angle that they project at,, like 90-120 deg. So In order to cover a number of sq ft the light must be raised to to a hight where the pattern covers the area you want to light up. So if you raise a 200w light to cover a 16sq ft area instead of a 4sq ft area, the light will be underpowered for good growth. Make sense?
the recommended hight above the plant tops is between 24 and 30" maybe less for flowering.
Now in your clase you have 2 lights of 200w each,, so you could move the lights apart to cover the 16 sq ft area, but it would be greatly underpowered.
I have a 2.5x2.5 tent and my 400w LED is barely adaquit. The only way to know for sure what light you are giving the plants is to buy a LUX meter off ebay (not much$) and measure the light falling on the plants at the top of the plant. You need 20,000 LUX min, for veg and 50-60,000 for flowering sun light on a clear day is 100,000 lux min.
and you're trying to match that best you can. Hope this helps.
