Thanks all! Yes my first grow, but I took a lot of time to research before hand, and I spend a lot of time with them. Most strains can go somewhat purple if the temps drop too much at night. However, some strains are much more vibrant to this color change and can change much easier. The strain I think the Sativa dominant is, Purple Haze, clearly has purple in her, so it really shows. As for knowing Sativa or Indica, it shows pretty early on which is dominant with height of the plant and adult leaves.