The leaves are yellowing, some are turning purple, maybe it's normal or maybe not, I don't know. If anyone could give me some suggestions. I decreased the light intensity to 75% because unfortunately I can't raise the lighthouse.
red and purple could be gentics and/or temperatures at night if too low can cause it -- different temps for different plants possible, but starts in upper 60s and below. Just autumn colors and no big deal. If room is overly cold during dark hours, maybe add some heat.
The yellowing i'd wager is nitrogen deficiency.
At first, I would have guessed a P deficiency. But if you're already in the last third of the flowering phase, the color changes can be completely normal.