Before I upgraded, I used to grow under a 400 watt. It will handle four plants no problem. I grew 14 in my closet one time and every plant got so heavy they were leaning on each other like drunks. I see bud sites on all the plants but they don't look like they are 6 weeks in, they look more like 2 weeks in. How close is the light? Can you add ventilation and get it closer? In the pictures, it seems to get pretty dim under the metal grate and those bud sites may not get enough light and give you " popcorn buds" if you veg next time, try a scrog setup with that metal grate to focus the light on that area. Personally I would remove anything below the grate that doesn't look promising so each plant can dedicate more nutrients and energy into the top cola.
When I grew under my 400, I often wondered if it was strong enough, and often blamed the light for shortcomings in my harvest. Smh. I had no ph pen, no ppm pen, I grew in home depot soil, the only thing I did right was buy some botanicare nutrients but then I'd come home and mix it with 8.2 tap water. And I STILL grew a decent crop. A 400 will work fine for growing but if you really want to make improvements. 1 use good soil like roots organics, happy frog, or in your case ffof, 2 get a ph pen, it's really important, your expensive nutrients are useless if not ph'd correctly. You will notice happier plants and bud sites all over. Happy growing!
