Carbon dioxide is recognized as a limiting growth factor and a potential health problem in RAS. Guidelines or recommended levels for CO2 seem to become more and stricter. 

CO2 building up in a RAS derives from mineralization of organic matter in the bio filter and from fish respiration, the largest proportion coming from the latter. One has to ensure as low levels of CO2 as possible entering a fish tank. For this IAA has developed a very efficient centralized Counter Cascade degassing concept.

In tanks: In cases with intensive production, build-up of CO2 levels can exceed guideline levels and it can be necessary to implement CO2 management in the tanks themselves. This can be done by either flushing out CO2, i.e. having higher water exchange rates in the tanks or by degassing in the tanks. IAA will in most cases recommend degassing in the tanks.

This is because with the combination of centralized and de-centralized de-gassing, water exchange in the tanks can be kept at 1,3 – 2 times per hour, i.e. we don’t need to flush out CO2 to maintain acceptable levels and we can avoid the quite significant increase in pumping and extra water treatment capacity otherwise needed with associated extra costs.

IAA is one of the few suppliers with a Total CO2 management concept.