Hey growers, this is my first topic and also my first grow. I will start with the basic info. I'm growing a "Sweet Mango Auto" in a hydroponic system. The Seedling is now 14 days old. It's just one plant, I decided to start slow. The nutrient mix is a Atami B'cuzz A and B Hydro all in one mix. I read about it, and what I understood, is that this mix has actually all nutrition's you need from grow to harvest. I also bought a bottle of calmag. I prepared a solution with 1ml of the solution per 1l distilled water and also adjusted the Ph to a 5.5-6. PPM was around 600., now 300. The temperature is between 28-30 Celsius ( 82.40℉ to 86 F) . I know its a bit too high, but the plant never had issues with it until yet. Two T8 growing lights with enough lumen and with full spectrum. Enough for the first 2-3 weeks until i put it on the balcony. I don't use a water or oxygen pump in the humidtydome. The plant sits on a rockwool cube 1 inch deep in the nutrient solution. Do I need to add some extra calcium or is calcium oxide enough? Now to the problem: Since 3 days , the leaves have a slight pale green color on the outside the leaves, from the halfway from the middle to the border. I was concerned and start to read a bit, and assumed that may a lack of potassium would be responsible. I mixed a new solution, because i assumed I made a mistake with the first one and created some nutrient lockup. Because in the B'cuzz hydro is already potassium oxide (K2O) included I didn't bothered to buy normal potassium. I hope it's the same. Please advise me if I'm wrong at this. Nothing changed, so I start to dig deeper, and found a interesting article that it could be overfeeding. it makes sense because my leaves start to curl weird as well. So I flushed the nutrition solution and put normal tap water for 24 hours to give it a rest and flush out the stuff. Today I woke up and got those yellow dead spots on the leaves. Now I'm on a point where I need expert help. Thank you all. F.