CO2: about 0.7 bubbles/second for 10 hours/day.
Water changes: about 80% per week. (It's crystal clear after a week, but I need to get access to the bottom for trimming.)
Fertilizer: 1 ml Seachem Potassium once or twice a week, 0.5ml each Seachem Trace and Iron once a week.
I live in Singapore, which is how I get away without a heater.