help deficiency or overfertilization?

Normaly light stress is what happened to my girls a few days ago. If lights to close first thing that happens is the tips on the top branches and new growth get bleached. Some see this as too much nitrogen when it is bleaching. If not remedied right away the leaves color starts to fade from the tips inwards. Pretty hard to get this to happen lower down on the plant as the light gets harder to reach down there. So if your seeing yellowing tips down farther on your plants unless you bleached those leaves as well as they grew I would say its excess nutes, building in your soil. But if your late in the flowering range I would just plain water from here on in until you see they need feed or until their ready , depending how close you are. Cheers