Seedlings 10 days from sprout - Stunted growth? yellowing leaves & browning tips

Ive done a couple grows in soil that were successful, so I'm not sure if I may be over-analyzing my current aeroponic setup but I am definitely in need of some advice. Any and all suggestions are welcome, please

I used the paper towel method to sprout seeds - took about 2 days.
Then placed sprout down in rock wool 1" cube. Seedlings took about 2 days to come out of cube.
The rock wool cubes were moved to 6in net pots surrounded by hydroton.
The seedlings have grown 2-3" above the 1in rock wool cube and its been about 10 days.
I'm using distilled water and adjusting pH to 5.7-6.2 range. PPM is less than 100
1000W HPS, Temp 79-83F, RO 40-50%. Genetics: Greenhouse Hawaiian Snow

At first i started to add 1/4 strength AN G-M-B along with Great White Mycorrhizae to encourage root growth.
I started noticing 1 little guy, the largest of the 4, had yellowing leaves and then all 4 guys started with browning tips, some less than others.
I immediately changed reservoir water to plain pH adjusted water, NO nutes. This was 2 days ago.
(SideNote on Great White: I have found that Great White powder substance doesn't do so well in my hydro setup because the powder does not mix well and settles after some time. Air stones don't exactly keep the powder suspended in the water...any suggestions besides using ORCA Mycorrhizae liquid)


Should I be feeding these little guys yet?
Another thing; would the 1inch rock wool cube cause drastic pH fluctuations that would affect seedling growth? I know rock wool can be acidic sometimes, but I soaked prior to using. Should I be watering from top to soak rockwool cube with pH adusted water?
Im not using nutes, but is Great White OK to add to the reservoir to encourage mass root growth?

Right now I think growth may be stunted, but I also may be over analyzing and thinking too much into the issue as these guys are so young.


Suggestions please??
Please let me know what you guys think...

I must note that the largest of the 4 little guys has a root that has not only grown out beneath the rockwool cube, but also out beneath the 6" net pot. This is encouraging that there is root growth, but this little guy also is showing the most yellowing in leaves. Also, has the largest brown tip leaf.
What am I doing wrong

they have radiation burns. i bet you have the HPS set to around 18 inches above them right? a freshly sprouted seed in nature does not pop her head up and then get exposed to the blistering rays of a 1000 watt hps. turn that big ass light off before they die. put a couple CFLs down real close to them, and hope they can pull through. if they put up new growth then you can raise that big ass light to 3 feet above them and turn it on, and slowly, lower it an inch or so every day till it is inside the 18" range. after that youcan raise the light to keep the tops in the optimum range for growth. that HPS is not the best choice for growing plants though. you would do better with 50/50 mix of warm white and daylight CFLs untill you are ready to flower them. if you try to force those little sprouts to flower they will probably just die.

Growing cannabis is not my regular bag, in fact im new to it, but those seedlings are classic sunburnt sprouts. even a baby cactus can burn like that if you just drop it into scorching summer sun when it's spent most of it's life in a shady garden center or nursery. you have to let pampered plants (and babies) acclimatize to scorching sun, or blistering HID lamps. the reverse is also true. if you took a plant grown outdoors in full sun into your house it would wilt, get all yellow and sometimes die. sudden changes in light intensity are the number 5 way to kill a plant.

1) over watering
2) over feeding
3) heat/cold
4) pests/pets (om nom nom!! Bad Kitty)
5) light shock
6) black thumb

Thanks guys. In the past for my soil grows, the guys got huge with the 1000W HPS.
I raised the 1000W hood until I can switch to my 600W MH setup.
I want to pickup a FLO T5 fixture to place inches above the these little guys.

Any suggestions on the Great White powder and how I can keep it suspended in the water to feed the root system so that it does not settle at the bottom of the reservoir? Any other suggestions besides the lamp proximity to the lil guys?

Thanks agin

just remember, its not the type of light, its the sudden scorching intensity on delicate seedlings. HID lighting on sprouts is like a baby in a tanning bed. wait, didnt that just happen recently? imma go look that up...

DAAAAAAMN! that bitch looks like old saddle leather, and the kid is a GINGER!!! thats tore up!

agree that that light is too much for those little guys i just did about 10 seeds three strains and started them under a 2 bulb T8 until nodes alternated on just potting soil and a rapid root cube feeding only distilled water with no adjustments and they turned into massive mothers by two months and they are still under and 8 bulb T8 now. i don't put under the big lamps till 12"-18"