{"id":567,"date":"2026-07-29T08:35:05","date_gmt":"2026-07-29T08:35:05","guid":{"rendered":"https:\/\/boostercompressorforoxygen.com\/recirculating-aquaculture-systems-and-oxygen-supply-why-continuous-low-pressure-compression-matters\/"},"modified":"2026-07-29T08:35:05","modified_gmt":"2026-07-29T08:35:05","slug":"recirculating-aquaculture-systems-and-oxygen-supply-why-continuous-low-pressure-compression-matters","status":"publish","type":"post","link":"https:\/\/boostercompressorforoxygen.com\/pl\/recirculating-aquaculture-systems-and-oxygen-supply-why-continuous-low-pressure-compression-matters\/","title":{"rendered":"Recirculating Aquaculture Systems and Oxygen Supply: Why Continuous Low-Pressure Compression Matters"},"content":{"rendered":"

The Dissolved Oxygen Problem in High-Density Fish Production<\/h2>\n

High-density recirculating aquaculture systems (RAS) represent the future of controlled-environment fish production \u2014 but they impose a critical operational constraint that conventional open-flow aquaculture does not face. In a recirculating system, the water is continuously reused, filtered and returned to the fish tanks. The fish biomass per cubic metre of water is dramatically higher than in pond or flow-through systems, which means the oxygen demand per unit of water volume is also dramatically higher.<\/p>\n

Standard surface aeration \u2014 diffused air, paddle wheels, venturi aerators \u2014 cannot maintain the dissolved oxygen (DO) concentrations that high-density RAS requires. Air is only 21% oxygen; even with perfect mass transfer, air aeration produces a maximum equilibrium DO of approximately 9 \u2013 11 mg\/L at typical water temperatures. A RAS stocked at commercial densities of 50 \u2013 80 kg\/m\u00b3 for salmon, or 100 \u2013 150 kg\/m\u00b3 for tilapia, requires sustained DO of 8 \u2013 12 mg\/L \u2014 and peak feeding events can spike oxygen demand dramatically above the steady-state rate.<\/p>\n

Pure oxygen injection is the solution. But pure oxygen injection requires a reliable, continuous, correctly pressurised oxygen supply \u2014 and the compressor that provides that supply is the component most often overlooked in RAS system design.<\/p>\n

\"LW
The LW series low-pressure oxygen compressor: suitable for RAS oxygen distribution headers at 2 to 8 bar outlet pressure. Compact footprint, 380V supply, continuous duty rated.<\/figcaption><\/figure>\n

How Pure Oxygen Is Used in RAS<\/h2>\n

There are three main oxygen delivery technologies in commercial RAS:<\/p>\n

1. Low-Head Oxygenators (LHO)<\/h3>\n

A low-head oxygenator (also called a packed column oxygenator) is a vertical column filled with structured packing material. Water falls down through the column while oxygen gas rises up in countercurrent flow. Mass transfer efficiency is high \u2014 70 to 90% of the oxygen can be absorbed into the water in a single pass. LHOs require oxygen delivered at relatively low pressure \u2014 typically 0.1 to 0.3 MPa (1 to 3 bar) above the water head pressure. They are the most efficient oxygen delivery method for large RAS installations.<\/p>\n

2. Speece Cones and Injection Cones<\/h3>\n

A Speece cone is a downflow contact vessel where pressurised water and oxygen meet in a conical chamber. Oxygen is dissolved under pressure, achieving high saturation levels. These devices require higher oxygen pressure than LHOs \u2014 typically 0.3 to 0.8 MPa \u2014 but achieve supersaturation, allowing the DO in the fish tank to be maintained above air saturation equilibrium. They are commonly used in salmon and trout RAS where very high DO targets are required.<\/p>\n

3. Direct Injection with Diffusers<\/h3>\n

Fine bubble diffusers inject oxygen directly into the fish tank or biofilter return line. This is the simplest delivery method and requires the lowest oxygen pressure \u2014 as little as 0.1 to 0.2 MPa above tank water pressure. Transfer efficiency is lower than LHOs (typically 50 to 70%), but the technology is simple and maintenance-friendly for smaller RAS installations.<\/p>\n

The oxygen pressure required at the delivery point \u2014 and therefore the pressure required from the supply system \u2014 depends on which delivery technology is used and the water head pressure at the delivery point. The booster compressor must be specified to deliver above the maximum system pressure requirement with adequate margin for pressure drop in the distribution pipework.<\/p>\n

Why Continuous, Uninterrupted Supply Is Non-Negotiable<\/h2>\n

In open-flow or pond aquaculture, a temporary oxygen supply interruption is a quality event. In RAS, it is potentially a catastrophic one. The fish biomass in a commercial RAS tank \u2014 which may represent hundreds of thousands of euros or dollars of livestock \u2014 can experience lethal stress within minutes if dissolved oxygen drops below critical thresholds:<\/p>\n