I have a 4x4 flood table top drip hydroton medium. I water 15 minutes on 60 off. I use 2 Mars Hydro Sp3000. It's day 3 of flower and just had some unwanted signs on my fans leaves at the top of the plant. Just trying to see if you guys have any idea what it could be. I thought maybe magnesium or calcium def. I used to use coco and just started doing hydroton. This is my second grow this way and the second time these appeared. I never could figure it out before and it just got worse and worse. No matter what I did. All the hydroton is brand new. I cleaned the hydroton as best I could and even ran the system with just water before transplanting the plants in. So therewouldnt be to much dust. I also soaked them for 48 hours in 5.8 water.