What Factors Determine Over What Time Span A CO2 Filling Lasts
Don't be confused or intimidated by the amount of influencing factors below. First and foremost, the knowledge should help you to use CO2 as effectively as possible. So that your CO2 fill lasts longer, and you can save money that way, too. The lifetime of a CO2 filling is related to the following:
 
CO2 Cylinder Size – The most common CO2 cylinders used in the aquarium hobby have a capacity of 500g, 2kg, 5kg, and 10kg for huge planted aquariums. The larger the CO2 cylinder and filling quantity, the longer it lasts. This statement does not contain any moving wisdom, but it is logical. The size makes a difference here and affects the time frame.
 
Aquarium Size – The more water an aquarium holds, the more CO2 must be fed into the aquarium to achieve a desired CO2 target value. Assume there is a 60-liter and a 120-liter aquarium, showing a steady CO2 value of 30 mg/l. Without further consideration, it may be taken that the 120-liter aquarium has the higher CO2 consumption of the two.
 
CO2 Addition Time – Regarding CO2 consumption, whether an aquarium is illuminated for twelve or only eight hours makes a considerable difference. At best, the CO2 supply should be coupled with the lighting time. We recommend starting the CO2 supply two hours before the lighting period starts. This approach ensures enough CO2 is dissolved in the water when the lights come on, and the plants immediately have the CO2 they need for photosynthesis. Further, the CO2 supply should end together with the lighting period.
 
CO2 Target Value – The CO2 value generally recommended for planted aquariums ranges between 20 mg/l and max. 30 mg/l. Assuming you want to reach 30 mg/l, more CO2 will be needed than if 20 mg/l is desired. The lifetime of a CO2 filling is, of course, also related to this value. We advise our customers to aim for 30 mg/l CO2 for heavily planted aquariums.
 
In addition to the factors already mentioned, there are others whose influence on CO2 consumption cannot be represented by a value. And yet they influence the end of the CO2 gas supply.
 
CO2 Bubbles Size – The tinier the CO2 bubbles emitted by the CO2 diffuser membrane, the more efficiently the CO2 can dissolve in the water.
 
CO2 Diffuser Type – There are different types of CO2 diffusers, which are either installed in the aquarium or integrated into the filter circuit of an external aquarium filter. Due to the extended residence period of CO2 bubbles in the water, CO2 inline diffusers and reactors in the filter circuit work more effectively than conventional CO2 diffusers.