Zenpaii said:

Hi my autoflower northern lights has been having issues with Cal mag def I added more Cal mag but it started to get worse I checked the ppm it was 1400! I flushed it last night and got the ppm down to around 400 I am not sure what my next step would be should I feed Cal mag a bit more and nutes at the normal strength again starting this morning or should I leave it later and feed tonight?

Also do you think this issue can possibly stunt it's growth considering it is flowering and at the start of maturing?

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Are you growing in coco? I have the same problem. The cal and mag can lockout. The ph must be kept in 5.8-6.3 range at all times. Drifting down and mag lockout occurs. Drifting up and the cal lockout occurs. Even within the proper PH range. My solution is use a base nutrient with 5-7% Calcium and minimum magnesium, 2% or less. Then use added epsom salts (magnesium sulfate MgSO4) 1 gram per gallon, added lastly to your nutrient solution. By doing this I can add or remove the epsom salts to chase a mg problem vs cal /mag problem. If you try to correct with the cal/mag preparations from the grow store, the cal/mag doesnt dance well together in the coco, which causes more lockout. The solution is to break them up. The plant needs more mg than cal. So if your nute mix has a good cal base %, use epsom salts vs cal/Mag preparations. Not to mention the added Nitrogen from some cal/mag juice, which causes N toxicity issues. Here is my 2 jack Herer Autos sprouted 7 weeks ago Aug20,2021, with banana kush sprouted 4 weeks ago Sep 10,2021. As you can see the mag deficiency on the back plant, with some cal deficiency on the front left plant. Autos are finicky. Same strain but 2 completely different Phenotypes requiring different nutes.