The cost is excessively high for what it offers as you will also need to purchase an electromagnetic valve (cost around 50 euros). A 2kg CO2 fire extinguisher bottle costs about 80 euros + 40 to 120 euros for a regulator with an electromagnetic valve and accessories (tubing, check valve, diffuser), leading to a final cost of 30 to 90 euros more expensive, but you save this money over time as the bottle will need to be refilled once every three to five months (cost of 15 euros). On the other hand, for medium-sized aquariums (50-80 liters), the nano system lasts about a month with the use of an electromagnetic valve, which closes at night and opens during the day. Additionally, this particular system is difficult to handle as the bottle runs out quickly and you constantly need to adjust the bubbles. In my system, the check valve did not work, and I never managed to make it work 100% as it should, even though I replaced the diffuser with a new one. Finally, I should mention that this specific system requires a lot of attention as you need to screw the bottle onto the valve, and if you're not careful, you may lose all the CO2 or even get burned from the rapid release. Ultimately, in my personal opinion, by spending a little more money, you can get something safer, more efficient, and ultimately more cost-effective from an economic standpoint

For small aquariums, it's great along with an electromagnetic valve to close it at night. It's perfect for someone who doesn't want big bottles in their house