how could you compare it though, if the stems are purple and they are short of nutrient, how could you tell if your buds were coming out a gram less each than what they would have done if they were perfect?
Keep yer nighttime temps a bit higher, i ran 6 Northern lights in low temp at nite and they got the pruple red stems, the ones b4 that i ran a little warmer, and they look regular green all the same seed lot