Product description: Brand new and high quality easy to set up CO2 system is designed for low cost planted tank use. What do you need to prepare for this systems? below(not included) 2x 2 Litre of Coka Cola plastic bottle 1x 200g of Citric acid or 200ml of vinegar 1x 200g of baking soda Tips to install: 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. DIY AQUARIUM CO2 SYSTEM Package included: 1 * needle valve 1 * pressure gauge 2 * bottle caps CO2 tubing