Yeah most likely you are correct. Now that I see there is a square area not growing as much with the other parts doing OK. It probably is the spectrum of light and most likely the uv or ir diodes must be in the center. I know my 100w spider farmer light with extra uv diodes. When I compare it to the other light I have if similar strength the spider farmer i always have to give the plants a smaller amount of umols. I was watching a video yesterday that said uv light you should only give you lr plants durrring flower and only for a few hrs a day. I suggest upgrading the light. I know mars hydro has a 150w light with bars it's on sale for less than 1oo I'm sure u ckd grow 2x2 pretty decent with that light