rusty leaves.

OK here I am again with the same problem as last grow although THIS TIME I'M USING CANNA COCO. LAST TIME WAS SOIL. OK folks il start with the setup. 4x4 grow tent 15litre fabric pots 4 Auto stardawg Ph 5.8 Temps on 27 off 21 Humidity about 46 lights on about 60 lights off Extractor fan and small...

OK here I am again with the same problem as last grow although THIS TIME I'M USING CANNA COCO. LAST TIME WAS SOIL. OK folks il start with the setup. 4x4 grow tent 15litre fabric pots 4 Auto stardawg Ph 5.8 Temps on 27 off 21 Humidity about 46 lights on about 60 lights off Extractor fan and small...

Can anyone identify this deficiency please. I'm growing in normal shop brought multipurpose compost(same as i always use). Problem started from seed. Only affecting lower leaves and is spreading up as the plants grow. Been told its mag deficiency. Gave them 3 liters of pH 6.2 yesterday with 2ml...