Whats this rust please

Fox Farm. All of the previous responses are accurate. You could add Dolomite lime to bring the pH of the soil up so that the plant would be able to pull up the Cal Mag and use it. You can chase this all over or change from fox farm. I was having this problem off and on in varying degrees. I was able to get to a harvest point but it was aggravating. it was stealing the fun from the project because of inconsistent results. The only thing that I changed was the soil that I was using and the nutrients I was using. The problem has completely gone away and the fun is back. I almost didn't say anything because I don't want to bag on a company and give them a negative review but I didn't want to watch you go through something that really doesn't turn out well in the end. Just take a look through the diaries where fox farm is being used and you'll see similar results. Don't get me wrong I've had really good results with Fox Farm and Ive got buddies who had really good results but then something happened and the pale yellow leaves and the rust dots started. Something changed there.