Weird spots on leaves

Hello,
Im growing a Shinning Lemon Haze under 600W HPS light, soil medium with perlite. they are fed Canna Terra Flores rnow at ~6.3 ph 4ml per litre. On 2 plants on the older fan leaves I found those weird spots, they look like calcium/magnesium defficiency but the rest of the plant looks good,healthy and happy. I think they occured even during veg, same ph of water, Terra Vega. Temp is around 25 deg, 45% RH. any ideas ?

I have the exact same problem and I also posted here two days ago. Someone said mag def and I watered with 1mg mag per liter today, yet to see changes. The leaves wont recover but I'll see if overall shes looking happy and if these spots dont spread. I'll report to you tomorrow. Cal/mag def shows always first on the lower, older leaves so that would fit. Always depends on how to water is in your area. If its really soft, then its more likely that its actually a calmag def.