Help plz. My girls are looking bad in the last 48hrs.

Can somebody please give me a clue as to whats going on here. Discovered the mites the night before i noticed something was wrong, sprayed them well with nighty nite spider mite and for got to feed them for 18hrs the day after. I also increased the EC level from 0.9 to 1.2 overnight the same time i sprayed for them pesky mites. Temperature reached over 28 degrees also as the door was left closed while i was away for about 12 hours. After i came back i noticed the leaves had lost colour and seemed to be reaching for the sky on about half of them, also the tips were dried out but not yellow at that stage, i figured it was from lack of water and heat. Just in case i returned the EC to what it was before that last night, but spots developed today. The tips seem to have burn marks on 6/10 of them running all the way up to the new growth and they also seemed to be stunted growth wise. Not surprising realy. Some of their lower leaves seem to be unaffected so i thought it might be that the 250w HPS was 1 1/2 feet from the tops despite the fact i have a strong fan constantly blowing the heat away from the bulb. Any advice appreciated

They need Potassium and probably Phosphorus as well. The leaves probably feel kind of thin and papery? That would be from K def. Something like a 2-2-3 fertilizer (correct pH) should help.

Im using Advanced hyroponics of Holland 3 bottle blend. Im using the exact combination it advises on the bottle for the volume of water. Im using hydroton pebbles with the original rockwool cubes i germinated in. I just bout an airstone today and plan to flood the roots to avoid dehydration again which i "think" may have been an issue. They have been semiflushed in a half strenth nutrient solution, and i now have the pots standing in the top resovior as show in my picture here. Are you sure its a def and not a surplus? as the high nutrient mix i had been watering them with by hand might have dried out, leaving nothing but raw highly concentrated nutrients in contact with the roots.

looks like nute burn to me! I noticed blueish tone which is an indicator to nutrient burn, the leaves curling up might be from heat stress but can also happen with nutrient burn. i would say as long as the temp at canopy doesnt exceed 80*F ish your good! +rep please! good luck!

Here is an idea of what i'm dealing with here.

I measure the temperature where the lights hit the top of the plants and its nearly always at 24degrees. The thing wrapped in tin foil is a lava lamp i use to keep night-time temperatures at around 20degrees. Is my water level high enough in the reservoir? This is my first time growing in this medium. Used coco peat the last two times and had no issues like this except for the first time i was growing and forgot to give them any nutes for the first three weeks as i thought the soil had trace nutrients. I learnt my lesson that time bout remembering nutrients but what happened on that occasion was they started going dry and yellow from the bottom canopy upwards. This time it seems to have struck all leaves except for the first true leaves on all plants.

And thanks to everybody that has posted so far. I really appreciate everybody's input

Would spraying for mites during the light cycle have caused any burning or is it 100% a temp or nute issue?

Because the single-bladed leaves on the bottom aren't as bad as leaves above them, it's not nutrient burn.

when you sprayed the plants did you leave water droplets on the leaves, because it kind of looks like perhaps theyre burned. If you spray them down at all, makes sure that there aren't any remaining droplets left on the plant. Im sure you're no amateur, but this is something that happens quite frequently to a lot of the plants I see with these kinds of marks. It's not always an obvious 'burn' that can be identified as a magnified water burn. Perhaps when you spray aim your fan more directly on the plants for a few minutes before changing it's angle.

Thanks again for everybody's input. After flooding the roots with the aid of my new air-stone and pump they seem to be looking a lot better. Do i have to be worried about root rot or mold having them this far into the water, or should it be fine like this until i start sexing the plant? I'm about 24 hours away from covering the top reservoir with white plastic to prevent algae from accumulating. Will this prevent root rot as well as guarding the roots from direct exposure, or will i have to do something else on top of it?

Big thanks to Mother's Finest, DocGonzo and last but not least EmeraldBuddah! My respect to you all, for helping me out. Good luck with your own grows guys!