Wilmeranswered grow question 4 years ago Hey mate, I really think it's nutrient excess. I have the same problem on my running cycle and same, the light is very far from my babies.
Just give them clean water and make sure to correct the PH to 6.5.
It's not 100% because you gave them too much fert, but probably the PH at 6 let this plant suck a lot of the nutrients that marijuana can "suck from PH 6 waters" so you have an excess now.
I'm trying to get rid of mine yellow tips since weeks, they do not go away. Today after 2 week I will give a bit of bloom fert to 3 plants and plain water the the others, let's see what happen.