Ne seedlings failing quick

I posted some problems before. I had planted and grew in a tote till they were a few inches high, then moved them to larger pots with potting mix in a grow tent with a Hydrofarm FLCDG125D Fluorowing Compact Fluorescent System. I found out that it was too cool and that the PH was way to high when I posted this question:
https://www.rollitup.org/marijuana-plant-problems/805687-plants-growth-stunted-leaves-browning.html

I followed the recommendation in that and a) added the Hydrofarm FLCDG125D Fluorowing Compact Fluorescent System expecting that the ballast and light would overcome the temperature, but they continued to wither and then got kind of pasty splotches as they did. and b) after it became clear they weren't going to come back, I got two new seedlings and setup the grow buckets as prescribed with the pearlite on the bottom and the coco on the top. The one sprouted a few days agao, and then the pointy leaves very quickly shriveled, and the oval leave has the pastey splotches.

What do I do now?!?!?!

Thanks for any input!

I've read about many people having problems with seedlings in coco, I believe it is slightly too acidic. My recommendation would be to start them in a very small pot with seed starting mix until they are established and healthy then transplant into the medium you described. I don't have direct experience with coco though so take it with a grain of salt and wait for other opinions. My guess is your PH is off and causing the seedling too much stress. A PH meter might be a good purchase.

The medium is far too moist. You should have much better results if you add 30-40% perlite to the mix, the roots like lots of air.

Hmm, before I wreck it, any better setup? Meaning going forward, should I plan on using coco / perlite mix, or is there a better option that I should go with. Also, is the rest of the setup OK, the bucket, the vent hole on the side, the peralite on the bottom?

Thanks guys!