*Help me diagnose nutrient problem (PICS)*

Hello everyone. I've been known to mess up while doing hydro/aeroponics because i don't have much experience yet, and i've burned my last grow pretty bad lol. I've noticed that my plants appear to be somewhat having a nutrient issue and would like help identifying and solving the situation. I am into week 3 of flowering my plants and running them at 70% nute strength. I'm thinking its due to either too much nitrogen, (leaves curling) or not enough Calcium (damage around tips)Here are some pics:

For this grow i am using:
Grand Daddy Purps strain
Aeroflo 36
House and Garden nutrients (for now Aquaflakes A+B, Drip Clean, Roots excelurator, multi-zen)
1 min on 3 mins off feed timer
40 gallon reservoir
40 ML of calmag (around 140 ppm before nutes)
1600 watts of light
the temp of the air stays around 65-70 degrees F
I'm not using my water chiller right now because its cold. the res temp is about 58 degrees F when the lights are on.

Extra notes:
A few days ago my PH shot up to around 6.4 (yikes), but i brought it back down to 5.9. I did flush with plain water before starting week 3.
After flushing i ran nutes at around 50%for 2 days after i bumped up nute strength +10% for a total of 70% nute strength.
My PPM was around 770 during this time and fell to about 630 2 days later (where its at).Anyways i would greatly appreciate any tips or advice from you growers out there.

3rd pic leads me to believe you're putting a little bit too much N in your mix...

thanks for the input. do you think i should hold my nutes here at 70% strength?

I'd have to agree with too much nitrogen...I'd reduce whatever nutrient is giving you the nitrogen by 50% and increase your P/K by 50%...you are probably good to bring your ppm up to 800-900 total.

They look a little heat/light stressed...you sure its only getting up to 75F under the lights at the canopy level? Do you have an osculating fan moving air around?

i dropped the nitrogen down and i'll have pics up later on this week. it gets around 70ish with the lights on, the lamp did seem a bit too close so i pulled them up a few inches. right now my PPM is 700. i'm worried i'll burn them so i'll be increasing the nute load slowly. im running week 4 nutes around 52% and about 15% less nitrogen

earlier this morning i still saw my leaves curling and panicked a bit and dropped my PPM to 400. i know thats really low for week 4 flowering plants, but i didn't want to risk anymore damage. i came home today and took some pics it appears that my plants are recovering from the slight nitrogen burn from a few days ago. Does anyone have any advice on when i should start upping my nute strength again and by how much? I'm pretty sure that it infact is HEAT STRESS that was happening to my larger colas, but the lower branches are still somewhat clawing. anyways i do not want my buds to be stunted too much due to the nitrogen error so if anyone can help me get back on track i would greatly appreciate it! i also double checked the light distance and moved my 1000w light 22" away from the top cola. I also have a 600w running next to it and pulled it up as well. I am using house and garden nutrients just incase yall are wondering