If you don't have a diary, could you at least give us some pictures in natural light? It's very hard to tell anything when the pics are purple. You mention "white powder" which might be powdery mildew... but there are lighter edges to your leaves that might be a phosphorus deficiency... and it may be BOTH - it's just REALLY difficult to tell with any degree of certainty. Do this - start a diary (even if it's only this week), put in some pics of the leaves and the whole plant under natural light and then ask your question again from the bottom of the diary...