Please bloody Help!!!

Heres two pics of My PPP Fem Nirvana
400w MH , Heat sits at about 25 celcius .
Light is at least a foot away.
Wtf Is the problem? These are a few weeks apart. One minute theyre lively and green next theyre all fucked up looking with taco leaves and pale green.
Any ideas? Ive tested Soil runoff and its fine. I drilled a few extra holes in the Pot just incase it needs better airation.But any other ideas?
Im feeding once-twice a week and waiting for soil to dry fully. Feeding Natural guano grow liquid. and superthrive.


Before




Now

Just wanted to add That i havent seen much new growth in the last two weeks compared to the other plant i have which has almost caught up to this one and is 3 weeks younger

What's your humidity?

lol humidity. Flush your plant with PH 7 water- 10-15 gallons through it. If that white shit is slow release ferts i would change the soil if i were you (it will take the control out of your hands and drop your ph) The browning on the tips of your leaves suggests overnuting. Ph is probably an issue as well. Im not much of a soil guy myself but i know whats wrong with your plant

lol humidity! Its nothing to do with the environment because all other plants are fine. Its a soiless grow medium , and those little white balls are styrofoam type things not time release fert. Also ph from runoff is spot on and all nutes and water are ph'd to 6.8 - 7.0.

It has been flushed and didnt improve at all. Growth is really slow.

i wish i knew but i will add be carefull with super thrive i use it and i have had probs in past with over doses that looked almost exact to your plants.