Btw I have a question for the 1st picture and 2nd picture. Did you plant all that HC or did it grow and spread.
I think it was mostly planted. I had another small 1.8 gallon tank with an HC carpet. I trimmed it every 2 weeks and just left the trimmings floating in that tank. After awhile, I sprinkled it on the bare patches and let the roots go down. 2 weeks later, i did another trimming an sprinkled it to fill in. Finally, I put on a thin layer of powder Aqua soil.
The HC is getting very long. I'm trimming it short and leaving the trimming in to grow into a very dense carpet.
I recently drained my 1.8 gallon tank due to mutant blue green algae. I'm in the same boat as you watching it transition to emmersed form.