Nitrogen?

A plant that is nitrogen deficient has for as long as I’ve been growing always started showing symptoms at the bottom of a plant, on the oldest growth and characterized by an even yellowing of the entire leaf on an overall pale plant and I don’t think that’ll ever change. So these other comments from the usual suspects are making me go like “WTF?” Guy’s common! Nitrogen is a mobile nutrient. Iron on the other hand is an immobile nutrient that’s will affect the top growth and more specifically the new growth. You know for certain it’s iron deficiency if the yellow leaf turns green again as it matures and problem remains on new growth. You most likely got this from a ph imbalance. Tap water usually has enough iron in it but plant can have a hard time absorb it if ph is ridding above 7.0 which is the case for most tap water. Guys who use tap water usually need to ph down where as RO users need to ph up. I understand it may be difficult to adjust ph without pen or strips but just a few drops of ph down In a gallon of water will make all the difference. Hope you all learned something. Please like comment if you find any value in this reply. Cheers 🍻