first growth here

Hi mate, what options does your LED have. If is has a veg and flower button, turn them both on and you may see a difference. The sun is what you are simulating and its not purple. You are looking for about 30W per square foot, so if you have a 4x4 your LED would be enough. Depending on the make though!!! If you really want to see a difference, have both the led and hps lights on and use the dimmer to adjust light on led's. From what i can make out your plant looks good but in future maybe take pictures without lights on as will show problems better. Happy growing and good luck...