If you use cal mag as prevention, for most manufactors dose should be 0.25-0.5 ml/L and in reality you should feed as prevention 3-4 times in all life span of plant.
I told you, rethink how you grow. Read a book, watch some video
Indica insitute
Weed in a pot
Mr canuks
And many more very informative chanels on YouTube, have a look.
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