over watering or cal mag deficiency

Hi Riu Take a look at this leaf. I think the problem may be from overwatering because the plant was okay a day or so ago until I watered it with two gallons in my thirty gallon pot. Another culprit may be my fan, I have it blowing towards my bulb to cool it and the leaf is in its current. Or it could be a cal mag defiency, which I know hardly nothing about, but I did get some cal mag that I will add next watering. thanks

neither by the looks of it. the picture isnt really very clear though..

I think this is overwatering. I currently have an overwatering issue with my dwc and my fan leaf looks exactly the same as yours. You can check it out on one of the pictures near the last page if you want. It looks pretty similar to me

just kidding there isnt a good picture of it, but it looks the same as my fan leaf looks today. Brown spots and some missing areas