The red stems are from nute storage, im not sure which nute, so its not bad, but im really not sure what is the cuase of all this. You deffinatly want to watch out for high ppm's nute burn can be a bitch. You would see fungus or anything posing a threat like mold around the base of the plant. I also tried to give some nutes as i havent becuase there young, and it seems like it just made the situation worse, if your seeing problems u want to jump back not add nutes, figure out what the problem is and correct it. leeching your soil might help and then add in what ever you feel should be stable. i dont work with cal mag or soil so im not sure. but browning spots and yellow leaves can be nute burn.