The fact that it can turn purple can be due to the phenotype or the temperature; when it drops significantly at night, plants can sometimes turn purple.
As for the clawing leaves, that can happen either from drying out or a slight overdose of nutrients. Are you still giving it a lot of nitrogen? Right now, it doesn't need much of that; it needs more PK.
Check your runoff; if the pH value is outside the range of 6 to 6.5, give it only adjusted pH water. Everything still looks okay for now.