Magnesium deficiency?

Como bien dices con Calmag lo puedes solucionar, te recomiendo el de Grotek pues es el que más hierro contiene, lo cual hace que absorba mejor el calcio y el magnesio, saludos

I'm not entirely certain, to be honest.... Your diary doesn't say what pH you're maintaining in this grow - and that's important. If the pH is between 6.0 and 6.3, then yes, some cal mag would maybe help IF it's a magnesium deficiency.. but again, to ME it doesn't look like that... magnesium deficiency starts at the tips and spreads solidly back up the leaf leaving behind dead and crispy leaves...and it also starts with the oldest leaves. It COULD be a calcium deficiency... but you'd need to figure out why you have it before simply throwing calmag at it... if the pH is below 6.0, that's your problem and you need to adjust it... if you've given too much nitrogen, that COULD be your problem... and if it is, you'd need to perhaps do a flush to get things back in line and then cut the nitrogen you're giving the plant to prevent another lockout... I won't tell you what else it might be... let's see if you can figure out the WHY and then adjust... If you've figured it out, you shouldn't see an increase in the damage to the leaves - but THAT damage will not be repaired... Good luck!

Yes you’re right, calmag will do the job

Calcium deficiency Cal-mag will help. You're welcome!