Plants looking unhappy! Help please!

[IblakesI]

Hey guys, I'm currently doing my first grow using rockwool 6'' cubes x5, Using a 5 gallon pot as a reservoir, feeding every 3 hours, about 8 cups each plant and not to waste. The nutrient breakdown is Big Bud( first 2-4 weeks flower) Calimag (when not using big bud), FloraMicro, FloraGrow, and Florabloom.
Growing 5 plants of some good ol' Colombian Gold. Average temp in 4x4 tent is {91 F} and average humidity is {40%}. The temp in reservoir with lights on is about 75F and off 69F. Using a 400w hps.

Now here's the problem....
I am about 2 weeks into flower and noticed some of the smaller bud leaves curling up, drying and having a purple/black color. All of this is happening at the top 1/3rd of plant.
Here are some pics, i cant post more if needed.

 

[dank daisy]

Your room temp is a bit too high. How close you have your hps? With that high of temp combined with the bulb too close could be drying them out. Not saying that's your problem. Just a thought

 

[RickityCrickt]

They look like you're having PH issues. The eagle clawing of the top leaves is a dead give away. I also think you might be giving it too much 'N'. Get the temps under control too bud. Jmo. Good luck.

 

[IblakesI]

Im assuming the N is for nitrogren?

 

[RickityCrickt]

Im assuming the N is for nitrogren?

Correct Do you own/use a ph meter?

 

[NuttyProfessor]

They look like you're having PH issues. The eagle clawing of the top leaves is a dead give away. I also think you might be giving it too much 'N'. Get the temps under control too bud. Jmo. Good luck.

i agree , the leaves also look too green , if in doubt flush them out ,

good luck

 

[labexperiment]

On top of everything else I believe I also see a potassium deficiency, does anyone else?

 

[NuttyProfessor]

i agree theres more than just N , maybe a lockout , flushing is needed