First ever grow!!

Week 3 = The Clown Show. I definitely transplanted too early into 14l pots. I also should have only started two seeds because this tiny tent is crowded now. I kinda freaked out when I saw what looked like nutrient deficiencies (calcium, potassium, I don't know) AND nutrient burn? I was so damn confused. I also realized not ph'ing was a dumb idea and quickly went out and bought a ph meter. I assumed since the tap water here is drinkable and not chlorinated, it's fine. But turns out it all comes from underground aquifers that are made of bedrock and every mineral that increases ph. I'm using lemon juice as my ph-down now and have figured that out pretty well. 1ml of it gets the water down to 6.0-6.3. Anyway, I spent the weekend in YouTube University trying to figure out what mistakes I made. More experienced growers, please feel free to comment with tips. Just don't be an asshole.