Define the biological load before selecting equipment
Record species, life stage, biomass, daily feed, temperature, salinity and effective volume. For RAS, include recirculation, make-up, solids removal and biofilter capacity. Oxygen demand changes with feeding, animal activity and microbial activity; a calm morning reading does not necessarily represent the critical loading period.
Agree objectives and limits with the aquaculture manager. A high concentration published for another species or short trial is not an operating target. Nanobubble studies provide hypotheses worth testing, rather than a transferable guarantee of survival, stocking density or improved growth under commercial conditions.
Treat oxygen addition and CO₂ removal separately
Measure DO at representative inlet, culture-tank and return points, recording temperature and salinity to interpret saturation. Check mixing and spatial variability. Oxygen addition can raise DO without providing the CO₂ removal needed by the circuit; oxygenation and degassing require separate assessments rather than being inferred from one sensor.
IFAS guidance explains that water conditions affect animals and biofilter function. Record pH, alkalinity, total ammonia nitrogen and nitrite, alongside CO₂ where relevant. The un-ionised ammonia fraction depends on the water conditions; an isolated total-ammonia result is not equivalent across different temperatures and pH values.
Use controls that distinguish the mechanism
Compare with the established treatment and, when investigating effects beyond oxygen concentration, with a DO-matched control. Keep feed, biomass, recirculation and husbandry comparable. Use independent experimental units and suitable replication: several fish in one tank do not substitute for several independent treatment systems.
Monitor over a period covering relevant cycles and loads. Where the biofilter is maturing, distinguish that trend from the generator effect. The cited RAS study used specific conditions and identifies a need for further validation; its findings are not copied as GENESIS™ performance or a commercial prediction.
Evaluate operation and continuity of the complete system
Measure recirculation electricity and gas supply alongside water-quality results. Check changes in solids distribution, filter operation and utility availability. Retain backup oxygenation and the farm’s response criteria during evaluation; running a trial does not remove the biological dependence on a reliable oxygen supply.
Acceptance can address stable DO, CO₂ and nitrogen, reliability and cost under equal loading. Growth, welfare and survival require specific assessment by the responsible specialists. Agree in advance which findings would justify continuing, modifying or stopping the trial, rather than selecting success criteria afterwards.
Common questions
Does more oxygen solve an overloaded biofilter?
Not necessarily. Surface area, maturation, pH, alkalinity and loading constrain nitrification. Identify the limiting factor rather than attributing every deviation to insufficient oxygen.
Can the degasser be removed when DO increases?
Not on that evidence. CO₂ and gas saturation require their own assessment. Verify the degassing function before modifying the recirculation circuit.
Sources and documentation
- Sean and colleagues — Air Nanobubbles Enhance Viable Bacteria Counts, Abundance of Nitrifying Bacteria, and Reduce Nitrite Levels in Marine Recirculation Aquaculture Systems, Fishes, 2025
- University of Florida IFAS — Fish Health Management Considerations in Recirculating Aquaculture Systems, Part 1
- FAO — Recirculating Systems and Re-use of Water in Aquaculture, oxygen supply and system design