What causes this?

Growing white widow and holy grail kush together. Kush seems to be doing well, but white widows is not looking too healthy. Both have been receiving same treatments, grow in 10 gal bags, ffof soil, water w kelp and molasses mix. ES300 LED about 24” from canopy.

Seems the kush likes the seaweed more then the white widow. Both plants are dark green which tells me there’s enough nitrogen and adding the tiny bit more with the seaweed might be starting to be too much for the white widow. Ocean forest should have enough N to get you through veg. Both plants look really good overall, I’d just use plain 6.5-6.8 water for a while let em use up what’s there. consider introducing a balanced bloom fertilizer when you start into the bloom phase.