Yellow Tint/Leaves on my plants?

First time grower, Im growing 4 plants in a 5 x 5 gorilla shorty , 1, godfather og, 1 bruce banner, and 2 northern lights, My Godfather Og plant has small yellow tips on a couple of the leaves and the Bruce Banner has a yellow tint on the tops of them. The other 2 plants in the tent (Northern Lights) look healthy. I will attatch pictures of all of them. Im using Octopots, have top watered once at planting and once a few days ago, theres 50ppm of clonex in my water underneath in the resovoir. Is it a nutrient deficiancy of some sort? Over or under watering? Light problems?

Alex Scheel (alex4808 — ImgBB < pictures

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This ones one of the northerns ^ healthy looking one



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