1st grow 9x Big Bud 640W LED

El magnesio es el encargado de la clorofila, si no hay clorofila no hay verde

Haven't used calmag, but my water is very soft so I guess that is one thing to do - but is this the cause?

Hey buddy. Looking through your grow and nutes strength you are using, I might have solution? Are u mixing all nutes together or giving them sep. As u are using a high dose of all key canna products which have enough of everything you'd ever need. You have nute lock or poor roots. That and you are using 5ml/l of 1 nute compared to half strength of all other nutes. When mixing nutes together you need to give exact mixes if you want to add extra of another certain nute just mix it up Sep in a 2ml/l solo mix. Also bring down the N, I can't tell what's in your nutes. But you are focusing too much and if you are giving them same nutes from beginning to start it'd be best to give them sep and mess around with doses as plants in flower love boosts in something as opposed to giving throughout the whole grow. Here's some info on the importance of PK and how they move water around your plant and the importance of flushing and mixing nutes evenly. If you need more info on m8ximg nutes I successfully mix 14 nutes together without constant nute lock, yes, I've had nute lock around 3 dif times on the same plant but if you watch your girls closely and slight change you catch and fix your plant will hardly have any notice. My lockout got so bad my ppm got to 8500 in 200ml of run-off so she was drinking the water taking some nutes but leaving most behind. https://www.360yieldcenter.com/2015/05/soil-nutrient-series-part-1-nutrient-movement-and-root-uptake/ Good luck pal