Is this nute burn - noob trying to learn

I think this is nute burn but as this is my first grow i dont know. or could it be genetics or deficiency as these were grown from bag seeds several different strains "mutts".
These are growing in a areoponic bubbler under 400 watt hps using
GH flora,micro,bloom and big bud
ph kept between 5.80 5.95
ppm 1124
temp 69 to 80.5 F
plants are 90 days from germination
5 weeks into flowering 1 week from flush.
a picture is worth a thousand words so heres a few. any help, opinions, comments would be greatly appreciated as this is a much needed medical grow.

from the way the tips are curling id say nute and maybe heat

Yeah looks like Nute burn or salt lock

Dr. Z what is salt lock ? how do you cure ?

salt lock or nutrient build up is caused when you use to much nutes and dont flush out your medium often enough. or just a build up from normal use of of all the trace elements and salts and minerals thats in your medium. when this happens flush out for a couple of feedings with a little peroxide and thats it NO NUTES. hope this helps

grodrowwithme - thanks for the info, i change nutes every week and top off with fresh water between. I think part of my problem is im growing in a modified areogarden and the resovoir is to small, causing th build up. Ive got a 18 gallon 6 pot bubbler/recirculator ready for my next grow which i think will do better. thamks again for the advice.

no prob i had a few probs with nutes untill i found out the truth to 2 an 3 part nute systems theres no such thing lol and you just got to be carefull im not to big on hydroponics im an organics man although i mess with a ebb an flow and dwc a little. i was thinking of doing an all organic soil drip system.