Hey,

My aquarium is 243 days old, holds 120 liters, and I've had a CO2 system connected to it from the very beginning. At first, I also had plants that really needed it. Unfortunately, they died anyway, and now I still have:
- Rotala rotundifolia
- Microsorum pteropus
- Cryptocoryne albida
- Hygrophila corymbosa Siamensis 53B
- Lilaeopsis brasiliensis
- Cryptocoryne crispatula
- Anubias barteri var. nana

Now for my question: Do I absolutely need the CO2 system? Or would it work just fine without it?

I use liquid fertilizer every day. Yesterday, my CO2 system almost killed my fish because the pressure always goes up when the CO2 tank runs out (I have a single stage regulator). That's why I'm a little worried about letting the system keep running like this. But since a dual stage regulator is expensive, I've been thinking about shutting down the CO2 system entirely.
Thanks in advance! :)