need help new growing shoots dieing back and shriverling up

i got a 1000 watt light above a floodtable theres 18 plants in 4x4 rockwhool cubes in pots, i got the table covered so the roots can come out of the pots im useing gh flora 3 expert series my ppm are 1300 and they been in flower for a week i veged for 4-5 weeks and the temp would get up to 85 before the exhaust to 78 so i lowered it to 77 when it kicks on and i raised the light from 17inches to 2 feet maybe a little more the plants are 25 inches and still growing but the new growing shoots on the top the tips of the leaves are dieing and shriverling back just at new shoots on top i dont think its a defienceys cause i got a good nutrients ive been doing the same thing for 5 years now and no problems until now the only thing i can think i did different is useing powder instead of liquid of ph down my ph is at 5.8 and rises to 6.1 i top off everyday with 2 gallons water and its a 35gallon rez, i just switched to the bloom nutez and i flushed with water inbetween switching so i dont wtf it is, it dont seem to get any better since then, at 7pm ill posts some pics, please help to many things been going bad for me lately and not this to, this just started about 2 weeks ago and its just the tops in veg my ppm were high like 1500 but they looked good

heres some old pics at 4-5weeks

heres the pics i hope its not nute burn

that last post is the only pic that i can find that looks like what i got it says heat stress with salt buildup with a lack of zn, fe,mn which i dont know how that can be cause i use gh nutez so im confused

ive been in flower for a week so when i change my nutez over to the bloom i flushed with water hopeing the blooms nutez and raising the lights would fix the problem i need to calibrate my ph meter, maybe its off causeing this problem i dont know but i need to fix asap

here some more pics

and some more somebody anybody can u help me

i hope this enough info i know somebody has had to have this happen before so please anybody give me a hand with this i need to correct this before i get to far into flower and my yields take a hit, thanks

How do the roots look?

to me they look find i posted a couple of pics of them a few posts back there white and look good to me

OK - I see them. They look a little stressed. Not much fishboning.

Might have the nutes too high. What are your temps in the res and are you using many airstones?

i think like 59 im not to sure i usually dont worry about the rez temp and i dont have any airstones either ive been running this same system for 5 years with no problems the first 3 weeks i didnt have any bloom nutez but i figure since i was in veg i was good but i got them after that and been useing them since

so nobody knows hun thats what happened to me to, the only thing i know thats different from the last 5 years is the ph down its powder instead of liquid and my ph meter needs calibrateing cause i think its off , i thought gh nutez where ph stables but my rez always rises from 5.7 to 6.0 which ant alot but i always lower it to keep it right everyday and top off with 2 gallons of water everyday, im going to look at it tonight and if its not any better im going to dump the rez and run water for 2 days and then start again but at 700ppm well see

all right i lowered the nutez to 1050 to me they seem to be doing better also its not every plant either i think my nutez got to high in veg like 1500 and with the glass not being in the lights it was a combination of things at the same time also like i said i vegged for 3 weeks without the bloom part of the gh 3 part nutez so i think its heat stress, nutez burn and a lack of mn, mg and the same damn time hahaha the same damn time, haha anyways well see how they make out

heres some more pics

wheres all my hydro wizards at

well i think i got it back under control for now, i thought maybe somebody else has had similar problems but i guess not u live and u learn

2-3 weeks