Scratched marks on leaves! Defiency?

Hello all!

It is growing like a beast and trained to have more shots exposed to light.
However i m recently noticing scratched marks on the sides of leaves.
I m using r/o water and giving cal mg at 1/4 strength, , could that be a reason?

Any suggestions/comments welcomed and have a great stoned day!

Ps: i previously posted this in the wrong sub forum of indoor grow room design, please remove that one if you see this MOD. Thx!
 
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