Young Auto leaves turning yellow

[MagicOr]

Hello all,
I'm new to indoor growing.
Having autos in soil, 3rd week from seeds germination.
just started feeding with Biobiz nutrition in the last 3 days.
Plants are in big enough pots, under 400w HPS lights, 18/6. Temperature is 28-30° daytime.
Humidity is about 40% (with lot's of work to achieve).
I'm attaching some pictures, please help me understand what is wrong with my plants.

[Canuck147]

This is a tough one - sounds like you have enough light, maybe the light is not close enough, maybe they didn't like the Biobiz. But my guess is 28 - 30 temps is too high for young plants. Hate to say it, but - at three weeks old your auto should be showing preflowers.

[Redwasp]

What soil are you using and what is the ph of your water? And yes i agree those look like plants that are not even a week from sprouting.

[MagicOr]

I agree, at 3 weeks they should be much bigger.
I'm really upset and must understand what is wrong.
I believe that the setup is fine. Lights are not too close and not too far. Had a small problem with air circulation, but already fixed that about a week ago.

could that be a really bad nutrition deficiency?
Or a really bad soil?
Too much or not enough minerals in the soil?

I'm using a dedicated soil. Just started feeding with nutrition is the last few days. PH is normal. Water quality is good. Did not test the EC. I feed them every 2 days or so, letting some runoffs.

Thanks for your help.

[Redwasp]

When you say ph is normal is it between 6 and 7? As far as soil I use fox farms ocean forest soil. I add at least another 15% perlite even though the soil already has it.

With fox farms ocean forest you do not need to add nutrients at least the first month. At that size you are very unlikely to be having nutrient problems. More likely root issues due to lack of oxygen in the soil if i had to guess off the top of my head.

[Redwasp]

That is caused by over watering, or soil that is to dense/compacted.

[Redwasp]

I forgot to mention that if you check everything and it all looks good you may have done nothing wrong. Sometimes some seeds/plants just fail to thrive. Most times its something that can be fixed but not always. Some people always plant more seeds than they want to grow because it happens.
Just dont give up. Keep reading the board. Asking questions and try try again. Just remember to have fun.

[MagicOr]

Yes, ph about 6.5-7.
I don't have the kind of soil you are using in my country.
I bought a dedicated soil for cannabis from a local hydro shop, and thought that there will be no need for adding nutrition at the first 3-4 weeks. But it seems like I was wrong. Leaves started turning yellow at day 15 or so, showing what seemed to be a nitrogen deficiency.
I started adding biobiz grow, and the new leaves are very light green. Today it's day 22, after 3 times feeding with nutrition, but I'm not sure if it's helping.

What do you think?

[Redwasp]

Just keep an eye on the new leaves. They will tell you the story.

[MagicOr]

Ok.
if I did solve the problem, how soon should I see some improvement?