plant problems please help!

i am growing the strain jack herrer in coco mix (mo"koko from holland).
i was told by my friend that this is the same as hydro because coco does not
retain or add any nutrients...it is merely a neutral medium for the roots to grow in.
therefore you should water once and in some cases twice a day due to the fact that
the coco dries out much faster and the plants are left with nothing to feed on.
i was watering once every 24 hours and just now started watering twice a day based on my grow
buddy's advice (seems to help a bit but not long enough to be sure). i have heard it is a danger to overwater in soil because this can cause root rot and fungus but was
told this is not possible in coco.
The plants have also been on vertical lighting (not sea of green) directly from vegging stage into budding(view pics: light in center and pots in a circle around)...i guess this could have caused them to stretch poorly
i am using ten inch pots, the room is well ventilated with a 6 inch carbon filter intake/exhaust and 3 fans
two lights 1000w hps and 600w hps 18 plants total.
temperature varies from 20-23 degrees celsius and humidity is around 65%-70%
i am using gh nutes which include gh micro, flora and bloom. i also add floraliscious bloom, kool bloom powder
and kool bloom liquid all from GH brand as well. i give one dose of calmag every 4-5 days, and regulate the water's ph between 5.7
and 6.0.
based on the pics i have attached it is evident that i am doing something wrong, many leaves are light green and many leaves also have shriveled edges, discolorations and burns although when looking at the stats all seems fine, and
my friend has grown the same clones successfully in a very similar medium...i know it is not a bug issue because i am in there everyday and have been looking for pests with a magnifying glass and don't see any anywhere...but it "looks like" bug damage to the eye
maybe a nute mix issue? i am following the doses on the back of the bottle and measuring accurately...
anyone have any suggestions or have had similar problems growing in coco? how much will this affect my yield?
should i flush them with water? they are currently 12 days into 12/12 light cycle.

if your following label feeding i think you should start there, i never liked GH's program, its very salty stuff, meaning will leave behind tons of fertilizer residue, IMO their recommendation is too strong, but first i would believe you need to flush with plain PH'd water, as your run flush water thru the pots, take a sample of the runoff and PH test it, this will let you know whats going on down there, i can assure you if you have a tds meter the numbers will be thru the roof and the rootzone PH will be night and day with your feeding solution, thus locking out nutes. flushing once a month for maintenance is always a good idea, but when using GH flora series i believe its critical to having a succesful grow

may also be some light bleaching, those plants are too close to those bulbs, i wouldnt have them that close even if i had a cooltube, your humidty is right at the thin line of where you can develop mold issues, when you start budding the humidty will rise to dangerous levels

Looks like light stress to me (different from heat stress).

Never heard of putting a 1000w bulb 10 or 12 inches away from the plant (atlease that's what it looks like in the pic). WHEW! That's a lot of light.

how cold is the air ur bringing in2 the room ?
and where and how fast is ur fans
by where i mean how close 2 the plants r they
coz i had my fan 2 close 2 the plants and the air
was 2 cold and it killed them
it looked just like urs ? ?
also i agree with what was said about ghe nutes
i used 2 use them but just the bloom and micro
using the lucas formula
but i found what was recommeded was far 2 strong
4 my plants and have now switched 2 canna

thanks for the replies i pulled them back from the lights and flushed seems to have helped a lot, bud sites still a little light green tho... i have switched the vertical setup to horizontal plants seem happier that way, leaves healing

I use GH coco, and i found that if you let them get dry, they will be way happier. i water about every 4 days and i am using 1 gallon pots. coco will hold more water than you think. use 1/4 strength nutes to start and gradually up the nutes to 1/2 to 3/4 strength. i never use full strength nutes with outstanding results. whenever i tried to go full strength i would burn the hell out of them.

Light burn/stress. Back up those plants.