When fish consume oxygen, CO2 is released in the water. To high carbon dioxide levels can negatively influence the fish growth or even be lethal. Therefore, it is important that CO2 is efficiently removed from the culture water. Degassing towers or active aeration are two principles, which are commonly used in aquaculture. Both methods are based on diffusion of CO2 out of the water into air.
When a large fraction of the CO2 must be removed from the water then the most efficient tool is the degassing tower, basically a low-height trickling filter. If higher concentrations of CO2 are tolerated diffuser aeration may be the most efficient tool.