hey KD I was reading back and noticed you're using the promix... might be part of your prob... it has tons of peat in it and even though the pH is fixed, peat holds water a bit too much and can contribute to weird def symptoms, especially in cooler temps.
Next time try my favorite mix, 50% composted manure and humus, 40% perlite, and 10% worm castings. The worm castings are a new one on me but my grower friend swears byu them and I'm coming around. The key though is LOTS of perlite and NO peat moss.
stinkyattic Reviewed by stinkyattic on . Why do I always see Red? All the plants I have grown always get red veins on leafs and stems, espically in the early stages of life. for example... 3.5 weeks old. All Sativa Dominant except the One Indica which has bigger fan leafs also the most purpal veins right up the stem of the small plant. ProMix with added perlite Ph 7, Ph Runoff was 6.5, Water with 2.5ml of Pure BLend Pro Grow per gallon, and superThrive, Ph 6.7-6.8. Water with every watering. Recomended Dose of Nutes on bottle is 7ml per gallon for Rating: 5