First grow first problem

Potassium deficiency maybe. The tips of older leaves start yellowing and moves inwards and older growth can turn red/purple, which is what looks like is going on with yours. Lack of nitrogen could cause the leaves to yellow and curl downwards but so can many other nutrient deficiencies. Maybe up the strength on the next feeding.

Co-incidence, these deficiencies have already been manifesting for the last 2 weeks.. What you add to the root zone takes 10-14 days to show in the leaf zone. Looks like the early stages of a potassium deficiency. Mega dosing won't fix any issue, weak feeding often is the best way to treat deficiencies. Quarter strength ever 4-5 days or so until improments start appearing, then normal feeding at normal intervals after that. Start a diary if you are thinking about asking more questions in the future, the more info there is, the better it is for formulating answers.