they usually start lighter green then get darker. looking good so far. use your EC/ppm meter to tell you how they are feeding: if at 200ppm, what is it the next day? if it's at 190ppm, thats good. they are eating and your ppm is pretty close. it at 220ppm, it's too strong, they are drinking more than eating if at 100ppm, way too weak. make it stronger. make sense?