the HC in my Spec is doing well, suprisingly, although its growing upwards more than sideways, but i believe thats because i've been too lazy with water changes. I dose EasyCarbo and TPN+ daily, when i remember.
The best thing you could have done is to leave the rockwool on and that would have anchored it as the HC grew.
I presume you didn't do that?? If not, then you're going to have to push it deep into the substrate and just leave a few leaves open and let it grow from there.
Yup always a tough plant to root unless you have something clay based which compresses and doesn't really move. If Ian's suggestion doesn't work try adding more gravel to the carpeting area.
Judging by your first picture above looks to me that you have a Cory or more in there. That may well be why you are getting clumps floating
Very hard to get something like glosso or HC to stay with Corys in there unless they are added after it has gotten up and running as they snuffle all over the place and knock it loose