Both of these are exactly a month old to the day. They've been doing phenomenal, and then all of a sudden these yellow spots starting showing up the past couple days. Some of the leaves are even starting to curl as if they've been burnt. Friend of mine who's been growing a while thinks it's "nutrient burn", but I haven't even added any nutes yet! I was planning to but now I'm not so sure. I wanted a second opinion. What do you guys think?
600w MH on 18/6. Light height: 20". In the room...Light on - 79-84 degrees..Light off 70-74. And I've been watering based on the stickys in the forums here. I don't THINK I'm over or under watering either but this is also my first grow so I could be wrong. Thanks in advance!