Hey there SanderAnders , you for sure have root zone issues which you can tell from the downward pointing leaf tips of the plant. Another problem you have is a micronutrient issue , this you can see from the top and newest growth discoloration (the CalMag is an immobile nutrient so the newest leafs are affected first) . To fix the root zone issue you need to break up the problem roots, this you can do by using beneficial bacteria which takes a long time or by using humic or fluvic acid which is much quicker and will not affect your existing microbe life in a bad way. To fix the calmag issue, just spray cal mag something like 1ml/L in a spray bottle at lights on twice a week for one or two weeks. If you do this , the problems will be fixed almost instantly. I hope this helps ! 🚀