High Neverscared,
The rockwool is too wet, this is a big problem from rockwool it gets saturated really fast.
What you need to do is get the rockwool out the clay pebbles for now. And only dip the lowest 20% in water with nutrients for 10 seconds everyday. When there are big roots comming out of the bottom from the rockwool you can place the block back in the pebbles like you have now.
When you need help or when you got questions you can always send me a private message!
Happy Growing! 😋