Hi mate, 30 degrees is not too bad, its on the high end but still a safe temp. As long as your RH is around 55%, you should be fine without AC. Adding CO2 is a great idea. My plant has had high co2 levels from the start and the growth is amazing. She will drink more water though. Im at nearly 1.5 litres every other day. I hope this help, good luck and happy growing