Seedling (8 days) - Leaf Discoloration (yellowing)

[John Kennedy]

Hi guys!
Just started this little guy and the leaves started turning a bit yellow...what could it be?

Soil - Biobizz Light Mix
Waterings - None (8 days old)
Strain - Critical Jack Auto
Temps - 20c - 28c
RH - 45% - 65%
Lighting - 180w LED (85w actual draw)

For the first 3 or 4 days the seedling was at 15 inches from led. It started stretching alot so now i have it at about 5 or 6 inches. Could it be light burn? I honestly have no idea, i've done everything 'by the book'..

 

[Waira]

..I think the light is too close,... seedlings don't want full intensity light right away... try backing the light up to 24" and watch the new leaves response.... only other thing that might cause something similar is hot soil or off-pH, but with Light Mix that's unlikely (All Mix might be too hot),... I see algae too, is this reused soil? Weird for it to form up like this in only 8 days,...

 

[John Kennedy]

..I think the light is too close,... seedlings don't want full intensity light right away... try backing the light up to 24" and watch the new leaves response.... only other thing that might cause something similar is hot soil or off-pH, but with Light Mix that's unlikely (All Mix might be too hot),... I see algae too, is this reused soil? Weird for it to form up like this in only 8 days,...

Thanks for the reply!
1) Backing off the light won't worsen the stretching? The seedling is already propped up with a toothpick from those first 3 or 4 days at 15 inches.
2) That's some eagle eye friend! I didn't even notice the algae, now i've checked they're there. Ok, the answer to this can only be because i was applying foliar spray with Biobizz Alg-a-Mic the other day, on another auto that's further along the way, and some mist must have travelled to that pot.The soil is brand new, store bought and watred with plain ph'd water 24h before placing the seed. No more waterings after that - one will be shortly, tomorrow or after.
Question: can the alagae burn the seedling? From what i've read i wouldn't think so, but i'm definitely in the learning-everything-i-can stage so...

Any help is much appreciated

 

[Waira]

...no, algae is a nuisance, and thrives where it's moist all the time,... might have been in the soil to begin with--- Easy to scrape it out so it doesn't much up the place! .... I can't tell how much it's stretched, but be sure it's in veg' lighting mode, and some stretch is fine, going top heavy happens on occasion too... get me a pic of it side shot,...I'll be back later!

 

[John Kennedy]

Also i double checked the light distance (led 180w - actual 85w draw):
First 4 days: 15 inches (seedling stretched to 2,5 inches)
last 3 days: 5 inches (stretching stopped, those marks appeared)
now: just moved it to 9 inches

 

[John Kennedy]

Side pictures, with algae visible.
First picture is after i remove top layer of soil.

 

[Waira]

... I'd follow what the manufacturers recommendations are for light distances (for example, look up Mars-Hydro), keeping in mind the lower intensity needs of seedlings,...of course, I can't see what the lights are like, but that wattage is hardly weak,...and I feel it's still too close..

 

[John Kennedy]

... I'd follow what the manufacturers recommendations are for light distances (for example, look up Mars-Hydro), keeping in mind the lower intensity needs of seedlings,...of course, I can't see what the lights are like, but that wattage is hardly weak,...and I feel it's still too close..

I know you're most probably right, but I have to ask something. Last time I checked (will do it again as soon as I'm home) the recommended distance was something like 20 inches. At 15 inches the seedling stretched so much it couldn't support itself.
My other problem is that I'm trying autos for the first time because this is a micro grow, which means I only have about 30 inches total vertical space. At some point they'll have to come a lot closer.
I'm at 10inches now for 24 hours still no spotting in new growth. You reckon that spotting is really light caused?
If so then I have to keep watch and pull her back away if spotting appears, right?
If by any chance it isn't light what else could I be (sorry I'd not making the best of senses I'm on phone)