Yellow Leaf Tips

I am about four weeks into flowering and on most fronts the plants are fine. Green and healthy, thick stems and good buds.

But many of the tips of the leaves - the very very tips - are yellowing.

From what Ive read, this could mean two very different things. On the one hand, it could be a K deficiency. On the other hand, it could be over-fertilizing, with excess evaporation drying out the tips.

But I am inclined to think its the K deficiency, because it seems to me the drying out from over-nuting occurs around the entire leaf, whereas this yellowing is only happening at the very tips of the leaves. Otherwise, the plants are happy.

Any thoughts? (sorry no photo but not at home now)

Thanks!