Leaves on 5 seedlings in dirt are hurting and I've good pix of the problem

Here's my legal med grow, 5 seedlings of 6 planted on Dec 5.

All sprouted in 1 day and looked great at first but now some of the leaves are yellowing/dying. I'm not prone to getting too worked up but their leaves are small and some are having a pretty significant problem. All are fem except the 1 that's bagseed who's sex is unknown. They were all sprouted in Grodan rockwool cubes under CFLs, then transplanted to 4" pots filled with Promix and watered with 1/4 strength bat guano. All are now under a 400w HPS running at 50% (200w).

Sam's OG (Bagseed)


Female Seeds Bubblegummer


Dinafem OG Kush


Female Seeds Lemon Kush


Afghan Kush Special


The AKS looks good, and the OG Kush looks good enough. But the Bubblegummer, Sam's OG and the Lemon Kush all have unhappy leaves. I figure the issue is likely one of the following:

1. some nute issue (but they're clearly not suffering from too much N, right?!)
2. Overwatering (but the soil's very airy, and I don't water but every 3 or 4 days...)
3. Too much light?! Don't think so but???

I've successful grows under my belt but a recent move means my supply is low and I've zero connections. So I'm really needing a win on this one. Any thoughts? And if addl pix are needed, please let me know and I'll GRD. Thanks all!

Ph problem or Nute burn are my guess

What is the 1/4 strength guano all about? That would be your issue i'm guessing. No real reason to give any nutes to a seedling, especially guano.

elkamino,
Leaf tip burn or discoloring is typically early nutrient burn. Just use water till they are much bigger.

In the future, and in my opinion, it's best to use a starter medium appropriate to the final growth medium. Rockwool for seedlings destined to hydro. Peat pucks or rapid rooters for soil. The rockwool buried in the dirt can cause stem problems.
JD

I bet y'all are right- nute burn. Thanks. I'll just keep giving them water. Don't know what I was thinking, just eager to get them jumpstarted with the guano.

I don't see a burn there.
I see a K def. in pics 1, 2 and 4, and N abundance in 3 and 5.

Thanks [FONT=Arial, Helvetica, sans-serif]Bakatare666. I agree symptoms look like it could be K def, but didn't think that was possible to be that advanced this early in their life.[/FONT] They're 2 weeks old.

Morning Elkamino,
Reading and diagnosing a plant problem is more then just matching the leaf to a picture. You have to look at the entire scenario. So you are correct...a two week old seedling is essentially living off stored nutrients in the cotyledon. And you can see them in the pictures. Still green. So that pretty much rules out deficiency. Plus the fact that you fed a seedling some guano tea earlier then you should have. So looking at those two facts...you can make a diagnosis almost w/o looking at the leaf.

And El...don't beat yourself up. It's a common new grower mistake. You have now learned that seedlings are very sensitive.
JD