Brown spots on side of leaves

White widow auto (greenhouse seeds),day 56,im growing in a mix of coco coir,perlite and peat ph:6,water ph is 5.9,I'm feeding light nutes(ghe trio)

Although she had an under powered grow during veg I recently got a 250w hps just a week after pre flowers started forming so she was still able to put on some size.
Today I noticed some brown stains starting to randomly form and I have no idea what they might be,could someone pls tell me what they are,also I have another spot which I think is a light burn but I'm not sure,any help on that would be appreciated as well

what are the quantity ratio's of your media ?

I'm not sure cause it's a pre mixed bag and it doesn't say the ratio on it(and I can't find it online either).
It's called New mix 2.0 by cannabiogen.
But I can tell that there isn't a lot of perlite in it...

i take it there is drainage holes in that bucket
if you look at the picture of the whole plant the top is light green and the bottom leaves are dark green, i would say you have cal/mag def
you say your ph,ing at 5.9 so your treating your media as hydropnic, try raising your ph to 6.3 for better uptake of MG
if those nutes are nitrate based do not let your media dry out completly or salts will build up on the roots and cause deficiencies

Thanks for the help
I have epsom salts at hand which I could use for mg,do you know a diy cal fert?I don't have any grow shops nearby and I don't feel like paying dumb amounts of $(unless I really have to)just to get a small bottle shipped here.

And yeah,first thing I did was drill the shit out of the bottom part of the bucket :'D

you might get calcium carbonate from a chemist shop, boil a load of egg shells up, where in the world are you spain ?

right to the west,Portugal

nice, im in the cold damp uk

haha,sun is already crazy strong here! gonna put some autos outdoor soon

Whole plant pic?

I wouldn't freak out just yet. May just be from the new light.

Maybe...
She was quite close to the light for a while(like 5-6 inches) but I was able to keep the temps at the canopy under 28c at all time