One plant yellowing in early flowering but others are doing great.

So I have 3 strains going.I have 2 obsession from world of seeds and they are doing really good ,just one of them has some slight clawing going but that plant always has and not effecting the plant.Then I have Grapefruit desiel from next generation and that plant is doing good also.
So this one plant I have is turning yellow and I'm at day 20 since I flipped to 12/12.
All I know about this strain is the person who gave me the seed said it was a purple.
All the plants are in 15 gal pots with ffof as a base soil.when I transplanted them from 5 gal to the 15 gal pots the plants where all put into ffof with added blood and bone meal,greensand ,and other amendments to make into more of a supersoil but I went easy adding the amendments just to make sure that the soil wasn't to hot.I water my plants with different teas as the plants where growing through different phases.Because I'm done with the stretch I am cutting back on the n and raising Pk in my tea for watering. I been keeping an eye on the plant and hasn't gotten worse in 3 days.Also this plant stretched the most.
So in your opinion do you think I'm Ok or should I raise the nitrogen I'm my teas.
Here is a pic.

Here's what I'd do... Give the one plant that is yellowing a light top dressing of alfalfa meal (say, 1-2 tablespoons), and then carry on. That way you aren't treating the other healthy plants for a symptom they are not showing.

You say that plant stretched the most, so it probably used the most nitrogen.

Thanks SpicySativa .Sounds good.I do top dress every third watering with the supersoil I have now.And last watering I did top dress it with about 2 inch. of soil.Will the leaves green up a little.or stay the same