Strange yellowing on leaf

[Rqsnlautoproblems]

Hi guys,

I was looking for some help, i have some strange yellow patches on my leafs and i'm not sure what thw problem could be.

Strain is nl auto
dwc with canna nutes
Now in week 6, i change the tank every week, started them on 1/8 dose, just gone upto 1/4, i was using cal mag at 5ml per 10 litre, but stopped now.

Be very grateful for any help

[9fingerleafs]

Tiny imperfections. All is well

[Rqsnlautoproblems]

Thank you for replying