Help my plants have red spots. Lots of pix plz help

Please help me my plants have burnt red spots on them i am not sure what it is. I am currently feeding foxfarm grow big, big bloom and hygrozyme. My ph is 5.9 and ppm's are around 500. The room temp is around 79 and humidity is around 40. Please help me out.

Looks like its starting to build a calcium/magnesium or iron deficiency.... add magical or calmag... that should solve your problem.... keep in mind that damaged leaves will not recover... look for no signs of deficiency on new growth. good luck!