Yosoo DIY aquarium planted tank CO2 system kit pro tube valve guage bottle cap D201 you need to prepare following(not included): 2 x 2 Litre of Coka Cola plastic bottle, 1 x 200g of Citric acid or 200ml of vinegar, 1 x 200g of baking soda the bottle must be carbonated beverage bottle, do not use pulpy, green tea, mineral water bottles, etc. trimming valve regulation avoid by sudden big or small, can't suddenly turn up, after immediately shut down again, so as not to cause abnormal pressure to the bottle. Note: Make sure carefully observe the direction of the parts before assembly. The usual wrong handle way will cause abnormal reaction components as follow: the contrary direction of the check valve and fine-tuning in the direct. easy to set up