Easy bud rqs , Hope first harvest!

Piet piraat piet piraat schip ahoy hoy hoy. You created a nutrient lockout inside the soil. The cause for this lockout could be a wrong pH or nutrient salts building up inside the soil. Both problems can be solved with a flush. Use 2 times the pot volume in water. Use water with the right pH and 50% from the given nutrients. Let the top 5cm of the soil dry out completely before watering again to prevent overwatering. Enjoy your grow!

Going too say high ph in my opinion they will be okay just feed plain ph water maybe touch of calmag if you really want

I would say its either rust spots or a root problem due too overfeed or high ph maybe. That being said what are your temps ect... during night ensure around 18° to help lower chances of bacterial issues with the roots which you may allready have. Luckily I've had this issue but not as bad, I'd suggest keeping lights slightly lower setting or higher if no dimmer, then feed plain ph water not even calmag! This will help flush some negative chemicals. I personally had minor spots which after a small flush essentially, they grew out and became healthy but this may not be the same for you as its alot worse than what I had