3 week old seedlings yellow/brown dry/crispy and deformed new growth?

[PuffinBlueClouds]

Hi, i'm brand new here, this is only my 2nd grow and just joined this site toady so apologies if i come across like an idiot.

Using coco 60/40 in all 3.
PH - 6.5

I have 3 seedlings all 3 weeks old
1 of them is perfectly fine but 2 look like theyve gone through hell.

fem - Zkittles in 3L - looking good
fem - Insane OG in 3L - makes you want to curl up into a ball and give up on life when you look at it.
Auto - Gorilla zkittles in 30L - Also makes me want to find my nearest bridge.

Now the zkittles which is fine has always been so, it's showed no signs of anything bad whatsoever in its 3 weeks.

Both the insane OG and Gorilla zkittles auto have been showing signs of some sort of stress for a good 2 weeks now with slow growth compared to the 1 good one as you can see in pics, and i have no idea what to do about it, ive tried everything from

Light intensity - Ive moved them further away multiple times and that hasnt helped plus turned down the wattage on the ballast, also hasnt helped. Im using a 600W HPS ( i know i need to change to LED fast) but it's well away from them, i started it at its lowest output of 200W and gradually increased the wattage now sitting at 600W but have never moved the light any closer, using the hand test to check for heat , it's nowhere near close enough to be effecting them.

Overwatering - I let them completely dry out to the point where the good zkittles plant started to droop as it was thirsty, so i don't think it's that.

underwatering - Im letting the pots get light then watering them until some run off, i don't see how i could give them more water.

Nutrients - The yellow leaves and brown spots started before i gave them any nutrients, i read that may be why so i gave them some at 1ml - Per L to play it safe, ( Coco Grow sensei A+B , B-52, Tarantula and Piranha) By advance nurtients , so could the new deformed looking growth be because of the nutrients ? i'm not sure.

Sorry if this isnt enough to go off but any help would be massively appreciated

Gorilla zkittrles in 30L fabric

Gorilla zkittrles in 30L fabric

Gorilla zkittrles in 30L fabric

Insane OG in 3L air pot

Insane OG in 3L air pot

The Superwoman of the group , not showed any signs of anything bad in its 3 weeks of life, not complained once, just grew her little head off. I just don't get it because i hav'nt done anything different to this 1 as i have the other 2 bad ones i just don't get it.

Not sure if this will be looked at by anyone but thanks to anyone who does, i appreciate any help i can get.

 

[PuffinBlueClouds]

Setup:
Soil - 60/40 coco pebble
PH - 6.5
600W hps
Advance Nutrients
Temps - 26 C (78F) Constant

 

[JIMKSI64]

Well to start you are treating a coco mix as a soil mix. Let's work on that part
Coco and pebbles will work fine but you need to understand your medium is inert and has minimal ability to store nutrition. Most coco is ran as a drain to waste or a daily/multi fertigations schedule. Tracking nutrition in and out as well as ensuring a balanced nutrition is all on you.
2 ways
www.growweedeasy.com
This can explain coco growing.
The other way is to use the 3 horizontal bars up top left for navigation and find forums then look for categories: then look for diaries. The grow diaries are packed with information. Use the spyglass to search for coco and whatever nutes you use and find a grower who has done that and has the pictures.

Good luck.

 

[PuffinBlueClouds]

Thank you for the reply, i appreciate you taking your time to help, i have spent the last 2 days reading through everything on the site you sent me, lots of very nice stuff i did'nt know which will be important for me soon, i just still cant get to the bottom of the bad growth on 2 of them.

 

[Randyy]

My guess would be that they are getting fried by that 600w HPS light!

For comparison, these ones has been grown under a 100w LED in about 8 weeks from seed.

So as you can see, they don't need a whole lot of light during the first many weeks.

Also what is the temperature in your tent? Could be a heat issue as well?! And what is the distance between the light and the plants?

Edit: I didn't see your second post. temperature should be fine as is. :)

 

[PuffinBlueClouds]

I could well be giving them too much light then maybe, the light is 34 inches away from the top of the tallest plant , which is were everything i read tells me to put it, why cant mine just look like yours ffs haha they looking nice , i can dim it down to 240W it just doesnt seem very bright at all.

thanks for the reply appreciate it.

 

[Randyy]

I could well be giving them too much light then maybe, the light is 34 inches away from the top of the tallest plant , which is were everything i read tells me to put it, why cant mine just look like yours ffs haha they looking nice , i can dim it down to 240W it just doesnt seem very bright at all.

thanks for the reply appreciate it.

You gotta keep in mind that the plants need for light changes as they age. They will need the most light in the flowering stage, so 34 inches may be the right distance later on, just not right now.

I made a ton of mistakes myself, so don't worry you will learn as long as you keep trying and before you know it you will be able to grow some top shelf weed!

 

[PuffinBlueClouds]

Turns out it was Nitrogen toxicity, for anyone else who suffers with plants looking like these, i flushed them heavily and 5 days later new growth has returned to normal, silly me, but im glad ive messed up as i now know what it is if it happens in the future.

 

[Randyy]

Turns out it was Nitrogen toxicity, for anyone else who suffers with plants looking like these, i flushed them heavily and 5 days later new growth has returned to normal, silly me, but im glad ive messed up as i now know what it is if it happens in the future.

That's awesome that you were able to fix it!