Review on BASE WAVE: CO2-Proof Tubing for Aquariums - Pressure Resistant Special Tubing with Trachea & Push Connectors by Lauren Morrison

Good quality CO2 cord, not too hard. yes you need it A regular silicone air hose won't work long term for a pressurized CO2 system (maybe yeast, but I've never tried). You need a tube that takes about 30psi to push CO2 through a ceramic diffuser. That's why you need that much stiffer and narrower hose. It's recommended to cut at a right angle with a razor and dip the end in boiling hot water for about 30 seconds before placing it on the barb. It's quite hard and may break the glass diffuser tip or something, be careful.