what can i do to fix

So im new to growing, and this is my first time ever growing ! I have this hydroponic grow box i bought for $580 (18 wide 13 deep and 4ft tall.) Im currently growing 4 ak47 feminized seeds that are 2 weeks into their grow. I am growing these 4 with another strain I do not know of. Theres sort...

anyone know what this is its on the one leaf and im preety shure it will eventually spread i transplanted a while ago and had a hard time doing so could that be the reason from shock