Just let her be man. Give her the best you can and she will give you the best she can, if you start trying to mess around with nute def/abundance it wont like it. All you're going to end up doing is sacrificing yield/potency while maybe turning a few fan leaves purple which are going to end up getting trimmed off anyways. I dont understand this obsession for purple and wanting to ruin a perfectly good plant to do so, as others have said get a known purple strain and hunt for a purple pheno.