This question was moved from the plant index section:
I can answer your question: No. CO2 additions are not necessary with Crypts... that said, CO2 levels and light intensity are important to remain in balance. So, if you have high light, it is important to make sure that your CO2 is sufficient.
Crypts are good plants for beginner plant keepers as they are fairly undemanding in terms of lighting, co2 and ferts. They do appreciate a good substrate to pull nutrients from, and in place of a planted substrate, you can use root tabs to supplement.