please help me with a deficiancy

I need some help. Im in a dwc. Running ionic nutes w superthrive. I had a rootrot problem because i had no benifitial bacteria in the mix. my resevoir temp was below 70. I fixed the problem with h202. I was told not to add the bacteria this late in the plants life. the are 8 weeks old now. now the leaves are turning yellow and one leaf on one plant is yellow with grey spots. The pic w yellow/red spots was from the root rot i think. i've never fixed a def. before. can someone help me pleeeeeeeease!

the h2o2 will kill any benifecals it touches you might need to lay off it and get on the bugs if you need something to battle root rot try roots accelerator

If the deficiency is showing up the younger leaves (as pictures) could be caused by an imbalance of magnesium. If the root system has been damaged you can foliar feed a micronutrient to deliver nutrients to the plant and the plant will deliver these down to the root system. From your photos it appears necrotic patches have started which also signals a manganese deficiency, hence a good micronutrient foliar spray would help.

thanks guys. the problems are begining in the older bigger leaves first then moving to the the younger ones. i am going to lay off the h202. please let me no if you think of anything else. these plants are 2 weeks into flower. let me know if you think i should bring them back into veg. untill the problem is fixed. not really sure if thats what i should do or not

I put the cal mag in w nutrient solution and upd my ppm from 480 to 990. i think i was starving my plants. I was just worried about burning them but we will see. im still running the h202 cuz i still noticed the root rot.

leaves are good now andgrowingsomebuttheroot rot is going to town. im still running 3 mils of h202, 29% inmy water every three days. i dont no what to do.