Oxygen and carbon dioxide in RAS system


There are various aeration systems to supply oxygen for an RAS system according to the article from Dr. Bill McGraw. 

Aeration system provide three necessary functions:

•   increasing dissolved oxygen,
•   mixing the culture water
•   diffusing carbon dioxide from the water into the atmosphere.

Owing to differences in designs, aeration devises have pros and cons that make them amenable to various RAS systems. 

1. Aspirator pump aerators, or any aeration device with a venturi : Most efficient oxygen transfer aeration devices that can be used for any aquaculture system, especially in saltwater. However, they are not very good at releasing carbon dioxide from water into the atmosphere due to lower turbulence. 

2. Diffused aeration or using air pumps with air stones or other such devices are rated the lowest in their ability to transfer oxygen into water while also being very poor at removing carbon dioxide as well.

3. The combination of aerator may be the most optimal, with some being better at oxygen transfer and at mixing and diffusing carbon dioxide from the water into the atmosphere.

Oxygen levels are normally maintained at a level above 4 mg/L for fish and shrimp and higher for other more sensitive species. Lower oxygen levels are much more dangerous with higher carbon dioxide levels as higher carbon dioxide interferes with normal respiration of aquatic organisms.

For more information, please refer to  https://thefishsite.com/articles/maintaining-water-quality-in-ras-the-essentials


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