Leaves yellowing and curling

could be nitrogen deficiency.. how long has it been just water?.. Zero feeding or flushing once you've already fed for a long time.. Can cause this the chasing issues.. Balance is important and you definitely wanna increase your feeding if your only doing water.. If your doing regular feeding and seeing a problem like this.. It's most likely from too much and not a deficiency. But you know your growing practices and nitrogen can be translocated by the plant so considerations have to be made about saturation.. Water.. The whole nine yards.. Plants should be drinking water a lot and with drinking comes the intake of nutrients this is how plants "eat". https://pediaa.com/difference-between-transpiration-and-translocation/