You’re overfeeding your plants, particularly too much Cal Mag .
The Purpling comes from the Mag excess and the weird spots are Cal deficiency, when there is too much Mag the plant can’t absorb the Cal...
Take it easy on the Cal Mag, once every 2 weeks is plenty enough in soil.
Try to follow a Feed Water Water Water Feed Water W W F ... schedule and everything will go right.
Hey bud. It's your first grow, just relax. Maybe a bit overwatered but no big deal. Sometimes you are better just leaving them to it. I know people will disagree but I noticed the more you mess will them over little issues, the easier it is to make the problem worse or another issue. They look 98% healthy to me. Your nutrient level looks spot on too, so well done. I don't even check PH but I am in soil. Peace and happy growing 😊
Mutant first true leaves is common when growing from seed. It gets worse with overwatering/heat stress, but they usually grow out of it.
Be careful tho, coco without a very good pH meter is hard.
Here is a link to a great pic of diffrent problems in the cannabis plant.
http://loudclouds.co/wp-content/uploads/2016/07/marijuana-deficiency-chart-jorge-cervantes.jpg
I hade the same like you and i found it to be a combination of a stressed plant that was rootbound and needed a bigger pot, i also hade overwatered it.
The leefs looks like that way when they are stressed in early veg, so if you can, change to a bigger pot so the roots can get more room and dont overwater.
Hello what I see looking at your picture are heavy leaves. Maybe from receiving too much water. To me the leaves should be upright and reaching the light not sagging. I can also see in between the veins on the leaves puffiness that goes to this point. Best of luck moving forward
Hey, first of all PPMs are way to high (im feeding @650 to my girls in flower) and i would also check a VPD chart, since that humidity seems low for early Veg. Hope it helps, best of luck (: