Yellow spots on leaves, what to do?

A question of a fellow grower:
I have is I’m getting yellow spots on the mid to lower fan leaves any ideas what is going on they just appeared in the last 12 hours ??

Blue haze, fem, indoors, soil, ph runoff?, fertilizer FloraNova grow 7-4-10 transplanted to large pot @ 2 weeks old being indoors the water and fertilizer schedule is about every 2 weeks, light 9 hours of sunshine and 5 hours under artificial lighting, temperatures 70 day and 60 night Ventilation natural, no Ac.humidity < 40 CO2 ??


What i do if i have any problems is first start off with checking the runoff ph and ppms i like my ph in soil to be between 6.3 and 6.5 and will your ppm is depends on what week your in i would need to no more to realy help but 90% of the time when i have problems is my ppm is to low or hi but i would chech that first and it could be that your plants could need more of something but there will be others that will will help to