I am very much enjoying the dialog in this thread.
The closest that I can come to the species of the crypts in your photograph is
Cryptocoryne albida http://www.wschowa.com/abrimaal/arac...yne/albida.htm
An item which I do not remember in any of my previous posts and which may be pertinent to this thread:
I installed two air diffusion bars and one air diffusion disk in my tank for the enhanced aesthetics associated with the air bubbles (I only "run the air" occasionally).
As at night plants become oxygen consumers instead of oxygen producers I turned on the air for a week at night as well as during the day.
I noticed some, but not a significant, increase in the growth rate of my plants.
This increase may have been due to the increased carbon dioxide induction at the water surface as well as the increased oxygenation of the water due to the surface turbulence.
(I could find nothing in the literature which discussed the possibility of increased carbon dioxide induction).