1st week 12/12, current feed 2.1EC (of which about 1.0EC is calmag - 5ml/gal). PH is always between 5.8-6.1, tent temp 25-27c, res temp 19-21c. Lights: COB 200w at 100% 75cm from canopy. More details in diary. Been spotting these dying leaves. What kind of deficiency could it be?