Do all aquarium plants need CO2 injection?
All aquatic plants need CO2 as one of their basic building blocks to survive and grow. However, some types like cryptocoryne plants are fine with the normal amounts of dissolved CO2 found in aquarium water and do not need extra CO2, while other plants like scarlet temple could benefit from CO2 injection but don’t require it. A third category of plants — which includes Blyxa japonica, dwarf hairgrass, and dwarf baby tears and other similar carpeting plants — has higher demands and necessitates the use of CO2 injection for the best chances of success.
For more information on CO2 systems in high tech planted tanks, read the full article.