That shitwool is your problem, I'm willing to bet !
Did you pre-soak it in 5.5 PH'd water.
Switch over to inert rooter plugs and see a big difference.
What was you rez's PH ?
What was the PPM during their death ?
What was your rez temps ?
After tap root shows, put into a pre-soaked rooter using a 100 ppm solution and 5.8 PH, but not too deep.
Fill half your net pot with hydroton and put the plug in, then surround it with the remaining hydroton.
I keep the top of my plugs level with the top of the pot when I put them in.
Put your water level, and maintain it, back at the very bottom of the pot.
You want the bubbles skimming and popping across the bottom.
If the top of the plugs dry out, put just a LITTLE water/solution on it, but don't drench it.
Once the seedling stands up and drops it's seed husk, start hand feeding/watering around the outer perimeter of the plug and up to the edge of the pot for 7 - 10 days until you see a tap root or more poking out the bottom of the pot.
Keep your PH between 5.5 and 6.2 at all times.
Below or above that and you begin to lose Nitrogen and Phosphorous respectively.
Keep you rez temps below 70, if you can otherwise buy a cooler.
After following these steps with success, I want half of the harvest as payment !!
LMAO.....just fuckin with you.
But seriously, you can do it so don't give up.
You'll slap yourself later because it will become so easy for you eventually.
