Trying to identify the problem

Just being on one spot not all the top leaves it might be a blight or rust it it was trace element I would expeckt to see it on all the upper leaves not just one section like that

He leaves or resting from too much calcium and it’s burning your tips and your leaves if there was yellow behind the orange it would be two less of an amount of calcium that they are receiving. When it’s dark orange like that in crumbling with no yellow pigment behind it that means they’re getting too much of it so you’re not under calcium plus in your plants you were over calcium which usually happens when you add Cal mag on top of fertilizer that has calcium already in it still a flush And only give 1.2 mL of Cal mag instead of the 2.5 to 5 like it calls for a need to fix itself. I had a mimosa cake do the same thing

Hi physicist, Usually that "rust" appears due to root problems. In your case I would say it's pH problem in the soil but check for other soil related issues...too compact? too moist (guess not since you only water once 3-4 days)? Good luck.

Hi there physicist, so i see you're on quite an "intense" light schedule. so what happens is the plant uses more Mg to regulate photosynthesis and what you're seeing now is a Mg deficiency. You can probably double or even triple your calmag , just reduce your N by a corresponding amount. If you do this the problem should stop spreading. You can also make a calmag spray 1mL/L twice a week because absorption is better through the leafs. If it keeps getting worse and you're already doing this , the only way is to lower the light schedule. But normally it should recover. Hope this helps ! 🚀

I would do what gmslave said and check your runoff to see what your medium is doing.

How often are you feeding your ladies with 750 rpm? Once, twice a week or more. if it is more you likely have some lockout happening. Check your runoff waters ph and ec and make sure each one is in the proper parameter for a soil grow. To high or low on ph can cause lockout and to high an ec can cause lockout

My 1st thought was potassium deficiency. But I would expect it to show up on more then one part of the plant. Your running the bloom feeds now which should have plenty of potassium in. It may be something that's not going to cause a problem. Keep your question open for a bit longer to see if anyone else can put there finger on it.