Category: Aeration & oxygenation systems
Product guide · OxygenationOxygen Cones for RAS — Specs, Sizing & Supplier Quotes
Oxygen cones — downflow bubble contactors — dissolve pure oxygen into a pressurised side-stream at 90%+ absorption efficiency. They are the standard oxygenation stage in RAS and high-density land-based farms. This guide covers sizing to your oxygen demand, the LOX versus on-site generation decision, and what drives price.
What oxygen cones do
- A cone-shaped pressure vessel: water enters at the top with injected pure oxygen and flows downward as the cone widens, slowing velocity until bubbles are held in suspension long enough to fully dissolve.
- Achieves 90–99% oxygen absorption at pressure, versus roughly 30–50% for coarse diffusers — the reason it dominates in RAS, where oxygen is a purchased consumable.
- Installed on a pressurised side-stream, typically 5–20% of loop flow, so only part of the flow needs pumping to cone pressure.
- Alternatives include low-head oxygenators (LHO), U-tubes and oxygenation in the pump sump; cones win where head is available and oxygen cost matters.
Typical specifications
| Parameter | Typical range | What it means for you |
|---|---|---|
| Absorption efficiency | 90–99% | The core selling point; verify at your operating pressure and flow, not at best case. |
| Operating pressure | 0.7–2.0 bar | Higher pressure means better absorption and higher pumping energy — the key trade-off. |
| Water flow per cone | 20–500 m³/h | Cone sized to side-stream flow, not total loop flow. |
| Oxygen transfer per cone | 5–120 kg O₂/day | Match to peak oxygen demand plus a safety factor. |
| Outlet DO | 15–35 mg/L in the side-stream | Blends back into the loop to reach the target tank DO. |
| Materials | GRP or 316L stainless | 316L for seawater and ozone service; confirm pressure-vessel certification. |
| Certification | PED / ASME pressure vessel | Often a permit and insurance requirement — confirm before ordering. |
| Instrumentation | DO probe, mass-flow control, pressure gauge | Automatic oxygen dosing to setpoint is what keeps consumption in check. |
Sizing guidance
Size oxygenation on peak oxygen demand at maximum biomass and temperature, then add capacity for the emergency case. Undersized oxygenation is the failure that kills fish fastest.
| Project scale | Indicative oxygenation duty | Design notes |
|---|---|---|
| Hatchery / nursery | 1 small cone or LHO, 5–20 kg O₂/day | Low absolute demand but zero tolerance — full backup oxygen supply required. |
| RAS grow-out, 200–500 t/yr | 2–4 cones, 100–350 kg O₂/day total | Cone per module plus a shared standby; automatic DO-setpoint dosing. |
| RAS grow-out, 1,000 t/yr+ | Multiple cones per module | Consider on-site PSA/VPSA generation with LOX backup at this consumption. |
| Post-smolt / high-density flow-through | Cones on the pumped side-stream | Confirm available head — cone pressure is only cheap when the pump already delivers it. |
Oxygen demand rule of thumb: 0.20–0.25 kg O₂ per kg of daily feed for fish respiration, plus biofilter nitrification demand of roughly 4.3 kg O₂ per kg of ammonia-N oxidised. Add 30–50% design margin for peak temperature, post-feeding spikes and future stocking increases.
How to choose
- Efficiency at your duty
Ask for absorption efficiency curves at your flow and pressure, not a headline 99% at a single ideal point.
- Head and pumping cost
The cone is cheap; the pressure it needs is not. Model the pumping energy over the project life before choosing cone over LHO.
- Oxygen supply route
LOX means lower CAPEX and higher OPEX with delivery dependency; PSA/VPSA means higher CAPEX, lower OPEX and a power dependency. Crossover typically sits around 300–500 kg O₂/day, site-dependent.
- Backup oxygen
An independent emergency oxygen supply with automatic low-DO release is non-negotiable and is checked by lenders and insurers.
- Certification
Pressure vessel certification (PED, ASME or local equivalent) plus documentation — retrofitting compliance after delivery is painful.
- Control and monitoring
DO probes with redundancy, mass-flow control to setpoint, alarm escalation and logging of oxygen consumed per tonne produced.
What drives the price
- Capacity and vessel size
Price tracks flow and transfer capacity; larger vessels step up materially.
- Material and certification
316L and certified pressure-vessel construction add substantially over GRP.
- Instrumentation package
Mass-flow control, redundant DO probes and PLC integration are a real cost line.
- Oxygen supply system
LOX tank, vaporiser and site works, or a PSA/VPSA plant, usually exceed the cones themselves.
- Redundancy
Standby cones and independent emergency supply are expected in a bankable design.
- Installation
Pipework, valves, supports and commissioning on a pressurised system are specialist scope.
Cone prices and complete oxygenation packages: not sourced. We have not found a dated public price source, so no range is shown. Price depends on cone size, pressure rating and certification, instrumentation, and the oxygen supply and backup chosen.
Common specification mistakes
- Sizing to average demand instead of peak biomass at peak temperature after feeding.
- Choosing cones without checking that the required head is already available in the loop.
- Comparing absorption efficiency figures quoted at different pressures and flows.
- No independent emergency oxygen supply with automatic low-DO release.
- Sizing the oxygen supply, LOX or PSA, before the cone duty is fixed, then buying twice.
Quote checklist for oxygen cones
State these in your request so offers are priced on the same basis. If you do not know a value yet, write “unknown” — suppliers must then state the assumption they used, and our team flags differences when comparing.
- Absorption efficiency — your required value, or “unknown”
- Operating pressure — your required value, or “unknown”
- Water flow per cone — your required value, or “unknown”
- Oxygen transfer per cone — your required value, or “unknown”
- Outlet DO — your required value, or “unknown”
- Materials — your required value, or “unknown”
- What it serves — species or product, life stage or grade, and the capacity it must handle (peak load, not annual average)
- Site and climate — country, water source, temperature and salinity range or ambient conditions, power supply
- Quantity, destination and timing — number of units, delivery point and terms, required delivery and commissioning dates
- Documents you need — manuals, test or performance reports and any conformity or electrical certificates required where it will be installed; no certification is assumed
Capacity, operating conditions, materials, quantity, delivery terms and installation scope change the price most — see what drives the price above. Send this checklist as a reviewed project request.
Components that work with it
- Oxygen generators
On-site oxygen supply for the cones
- Water quality sensors
DO probes control oxygen dosing
Plan before you request quotes
Free calculators give a first sizing or cost scenario from your own inputs. Results are estimates to discuss with suppliers, not quotations.
Oxygen cones — buyer questions
Get quotes for oxygen cones
Send your duty, site conditions and target capacity once. We turn it into a comparable specification, send a confidential RFQ to producers and suppliers that may fit the project, and coordinate their replies on the same scope. Free for buyers; qualifying projects start at USD 250,000. FishMatch does not manufacture equipment, and buyers do not contact suppliers directly.
Related pages
Sources and review
Ranges marked "manufacturer-stated" come from public manufacturer documentation reviewed by FishMatch; they are examples, not guarantees, and supplier names are not shown. Last reviewed 2026-10-24.