On the AFA website here: Aqua Forest Aquarium , it states that Ammania sp. Sulawesi needs medium CO2. I have no idea what that means. I come from the lowtech world, and the most extensive thing I've ever done is add root tabs to the substrate. I don't have space in my room for a fancy co2 cylinder, and it'll look like a weird science experiment if I use the 2 liter yeast trick (and again, limited space). Do I really have to supplement CO2? Why? I'm DSM'ing a 2.5 gallon right now, and the only intended plants are the Ammania and HC. Would it be okay if I just ran a filter/airstone on the tank to increase gas exchange? Why would that work/not work? If it helps, I'm also using Fluval Shrimp Substrate, and might supplement with some Flourish tabs, which should leach nutrients into the water without me having to add liquid/dry nutrients.
All plants need a carbon source. Do you need to add CO2 artificially? No. Respiration and atmospheric equilibrium adds some. But if CO2 is low and light isn't sufficiently high to compensate for it, then it may eventually due.