Please help !!!!

hello everyone..
i have a 4 bucket DWC under 400w Mh
3rd wk veg.
Ph @ 5.8
ppm around 500
rez temp 76
air temp 78
Rh 60%

my problem is that i have curling tips on a few of my gurls as well as "discoloration" on on some leaves..like a lighter green?
4days ago i changed my water in all buckets and upped my nutes (AN sensi grow)
from 1 1/2 tbsp (last week) to 2 1/2 tbsp this week.(thats each part a/b) so total per bucket is 5 tbsp....should i scale wayyyy back on nutes? could this be my problem..i was going by the AN calculator it said for a 3 gal rez = 1.76 fl. oz
i converted to tbsp and got 3 1/2 tbsp...
heres pix..
i appreciate any feedback..thx guys!!!

It does look to me like you may need to scale back a lil on your nute strength.
How were they looking b4 you changed the dosage? I've found that a lot of times you need to go more by how your girls look than by a feeding chart. Those are just guidelines to give you an idea. Not alla strains are gonna need the same levels at the the same time.

Going from 1.5 tsb to 2.5 tsb is a 65% increase in nuts. I always increase my nutrients slower then this. And 76f is way to hot for your rez. You need it between 65f and 68f.

thx for the advice guys...i do need to pull back on nutes ..maybe flush next rez change then wk after decrease nute strength? ill try and get a handle on rez temp. whats the best way to lower temps?

A Cooler system is kind of costly. Or you can just drop two liter bottles of frozen water in there twice a day or what ever it takes.