Agreed. Just keep an eye on that yellowing.Definetly a Phosphorus defiency! But i don't think there's a nitrogen defiency. Not yet. But it may come in the next weeks so i would monitor this as well. At first i would deal with the phosphorus.
That the whole point! The leaves turn purple to signalize that they want be green againWill they go green again from purple after deficiency is fixed?