If it’s new new. Probably light. Another possibility is could be cal/mag. Check your tds every feeding. Cal/mag takes 4-6 weeks to show a deficiency after it’s already started. Recommend great white rooting powder as to help roots absorb maximum nutes and grow very robust. Good shit. For all your smoke gear head to savsmokes.com. Gonna need a nice bong and some hemp wick to enjoy your buds once cured.
It’s not calmag, or at least not Ca. Ca deficiency is usually brown necrotic spots on the leaves. It could be Mg, P or K, question is, is it a deficiency to a lockout, and if a lockout, why? More info on soil, nutes, watering, and light needed