What's up w/ my baby?

This is my first attempt at hydroponics.
CocoGrower 6 gallon unit.
400w HPS Digital Ballast.
Pineapple Express feminized from Attitude.
Germinated for 32 hours until taproot was 3/4 inch long then placed directly into hydroton. After 2 days it has grown about 1 and 1/2" and has began to grow its first set of true leaves. However the leaves are curling under. I have a Skunk #1 going right next to it and its doing great compared to the PE. Same conditions, same germination, etc.
Temperature is usually between 80-90 depending on time of day and if the light is on or not, and if I have the fan blowing. I'm using tap water and the PPM for it is 54. The PH is 6.8
Here are a few pictures of the PE. The one that isn't a close up is day 2 of its life after placing the taproot in the hydroton. The rest of the pcitures are from a couple of hours ago on what is now the beginning of day 4. View attachment 1401567View attachment 1401568View attachment 1401569View attachment 1401570View attachment 1401571

Okay today it looks a little better as the cotyledons are still curled under but the first set of true leaves are about double in size.
Temperature - 79 F
Humidity - 32%
First four pictures should be the PE that is having the issues. The last two are the Skunk #1 that looks "healthy" to me. Any ideas?
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57 views and no replies? Odd.
No love for the n00b?

You may want to ph down the PE a little. maybe that's y the diff in growth between it and the skunk (also maybe because the skunk has more sativa genetics and is just therefore more apt to grow faster genetically) maybe try to get it down around 6. but your set up seems good. I'll be lurking around.

Thanks for the info, glad to see someone interested and trying to help.
I think the humidity and the PH were the problem, as I adjusted the PH and raised the humidity by 20% and she's look a bit better.
Just posted some pics of day 6 at: https://www.rollitup.org/grow-journals/403330-g13-pineapple-express-ufo-skunk.html
Not that great of pictures but ah well.
Thanks again.