UPDATE (changes & improvements)
Have been pleased with the growth and progression of this set-up. A few plants have been added and subtracted (mainly because of size).
No heater in this nano. Temperature stays fairly stable in ambient room temperature (72-76F). I noticed temperatures rising to 80F during a couple of recent hot/humid days, which got me thinking "to expect the unexpected". Installed a small fan behind the tank knowing the "scorchers of summer" are right around the corner. Tried the fan out and was able to drop the water temperature around 4-5F in a short period of time.
CO2 levels have been consistent, but never have been completely satisfied with my diffusion (using a glass nano diffuser). No problems with the diffuser itself, it produces very fine bubbles. Just unhappy with the CO2 distribution (tried different flow patterns within the tank, feeding the CO2 mist through the intake of my circulation pump, and tried different placements of the diffuser within the tank). Always the same result: a lot of CO2 bubbles rising to the surface without being dissolved.
I came up with an idea to help improve this problem... mounted a very small pump near the diffuser with a 90 degree fitting on the pump's output. Water discharged from the pump pushes down directly over the top of the diffuser (kind of like a downdraft). Bubbles rising from diffuser are constantly forced downward, over and over again. After doing this, there appears to be no CO2 bubbles reaching the surface. Any bubbles that do escape and`start heading toward the surface are captured by the pump's intake and forced down again. I do notice a few bubbles circulating around the tank, but they are almost microscopic in size. Another pump is used on the other side of the tank for circulation and surface flow.
The circulation pump on the other side
has been growing (and flowering) at a steady pace. The Buce's with their roots buried in substrate are growing faster, and seem to have more of an upright growth pattern.
'Buce' tied to rock and wedged in rock wool.
Started to gradually shift back over to stem plants in this set-up. I plan to eventually turn this tank into a 'dwarf cray' playground (wood, rocks, various moss species).