Solids collection system (a rotary drum filter)
A rotary drum filter removes suspended solids, uneaten feed and faeces first — the mechanical first line of defence.
Recirculating Aquaculture System
RAS system
A complete, plug-and-play land-based recirculating aquaculture system — drum filtration, protein skimming, biofiltration, UV/ozone sterilization and oxygen injection pre-assembled into one module, so you can rear fish or shrimp indoors with full water-quality control on a fraction of the water.
- Capacity5–30 m³/h · turnkey scale-up
- FiltrationDrum 50–200 µm
- BuildPP / UPVC / SS304 / SS316
- WaterFresh & saltwater
ISO 9001 CE OEM / ODM
15+ years in aquaculture engineering · Trusted by Japfa Group, Japan Nissui & Tropo Farms · Shipped worldwide in one container
Product Description
An all-in-one system for indoor fish & shrimp farming
The integrated RAS equipment is a complete system designed for simple setup, easy maintenance, and reasonable cost. The design is flexible for a wide range of applications including saltwater or freshwater holding, rearing, aquaponics, and more.
We can make a reservation according to the customer’s request. a land-based integrated RAS equipment consists of purification units, each cleaning the water in sequence before it returns to the culture tank.
Advantage
The protein skimmer, UV sterilization, and bio filter are the core devices. The all-in-one RAS equipment has a perfect performance structure, and a small footprint, and it is energy efficient, economical, safe, durable, and easy to maintain. This small RAS system is designed specifically for small systems such as a processing capacity of 5 m3/h, 10 m3/h, 15m3/h,20m3/h, and 30 m3/h, which require flexible movement and convenient connection.
Specifications
Models & configuration
Indicative configuration integrated from the standard 5–30 m³/h range and industry practice — final specifications are confirmed per project.
| Model | Capacity | Typical use | Core configuration |
|---|---|---|---|
| SIGMA-RAS-5 | 5 m³/h | Hatchery / research / pilot | Drum + skimmer + bio-filter + UV |
| SIGMA-RAS-10 | 10 m³/h | Small farm / holding | + ozone + oxygen cone (option) |
| SIGMA-RAS-15 | 15 m³/h | Small–mid farm | Full 6-stage chain |
| SIGMA-RAS-20 | 20 m³/h | Mid-size farm | Full 6-stage chain |
| SIGMA-RAS-30 | 30 m³/h | Mid-size / multi-tank | Full 6-stage, parallel-ready |
| SIGMA-RAS-60+ | 60 m³/h and up | Commercial / industrial | Custom turnkey engineering |
| Process flow | Inlet → drum mechanical filter → protein skimmer + ozone → bio-filter (trickling + submerged) → UV → oxygenation → return |
|---|---|
| Mechanical filtration | Drum screen 50–200 µm (typ. 70/80 µm, 316L SS mesh) |
| Main materials | PP / UPVC / SS304 / SS316 (316L for saltwater) |
| Disinfection | UV sterilizer (e.g. 120 W = 3×40 W class) + ozone generator (e.g. 3 g/h class, optional) |
| Water type | Freshwater / saltwater |
| Options | PLC control, online water-quality monitoring, auto backwash, oxygen cone / degassing tower |
System composition
Purification units, working in sequence
A foam fractionation unit (a protein skimmer or dissolved air floatation device)
Strips dissolved organics and fine solids out of the water before they break down and load the biofilter.
Bio-filter
Nitrifying bacteria on high-surface-area media convert toxic ammonia and nitrite into far less harmful nitrate.
Protein Skimmer
A core device that lifts dissolved proteins and organic waste out of the water column as foam.
Sterilization system (UV sterilization or ozone generator)
UV and/or ozone kills bacteria, viruses and parasites, keeping the recirculating loop biosecure.
Oxygen injection system
An oxygen cone / diffuser raises dissolved oxygen to support high stocking densities.
Pump
Pumps the clean, treated water back to the culture tank to complete the recirculation loop.
brushes
Bio-media brushes add protected surface area for the nitrifying biofilm to colonise.
Application
Where SIGMA RAS systems are used
- Indoor / land-based recirculating culture of tilapia, seabass, grouper, trout, sturgeon, shrimp and crayfish
- Hatcheries, nurseries and research / pilot platforms for high-value, water-sensitive species
- Saltwater & freshwater ornamental breeding, live-fish holding and transport
- Aquaponics systems integrating fish culture with plant production
Gallery
Inside the integrated RAS module
Video
RAS system
Logistics
Package and Shipment
Modules are skid-mounted and pre-assembled, so on-site work is mostly connecting inlet/outlet and power. Every system is crated for export and can be consolidated into one container to your port, with installation guidance from our technicians.
FAQ
Frequently asked questions
What is a recirculating aquaculture system (RAS)?
A RAS lets you grow fish or shrimp indoors, year-round, on a fraction of the water a pond or flow-through farm needs. SIGMA’s integrated RAS chains mechanical drum filtration, foam fractionation, biofiltration, UV/ozone sterilization and oxygen injection into one pre-assembled module.
How does a RAS work step by step?
Water flows in sequence through solids collection (rotary drum filter), foam fractionation (protein skimmer), a bio-filter that converts toxic ammonia and nitrite into far less harmful nitrate, UV/ozone sterilization, and oxygen injection — then clean treated water is pumped back to the culture tank, completing the loop.
What size RAS does SIGMA offer?
Standard small systems are built for processing capacities of 5, 10, 15, 20 and 30 m³/h, with larger turnkey systems scaling to commercial farms. Each system can be configured to your species, density and site.
Can a RAS be used for shrimp or crab farming?
Yes — the same recirculating design suits fish, shrimp and crab, and can be configured for saltwater or freshwater holding, rearing, nursery, grow-out and aquaponics.
How much less water does a RAS use?
A closed RAS loop reuses treated water, so it needs far less exchange than pond or flow-through farming — a major advantage where water is scarce or temperature and disease control matter.
Related equipment
Components in the RAS chain
Automatic Rotary Drum Filter
Self-cleaning rotary drum filters for RAS & aquaculture — automatic solids removal, multiple flow rates & micron options. Factory-direct from SIGMA. Request sizing & pricing.
View details →
Protein skimmer filter
Industrial protein skimmers / foam fractionators for RAS & marine aquaculture — removes dissolved organics, improves water clarity & oxygen. Factory-direct from SIGMA. Get a quote.
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Biological Filter
Moving-bed & media biofilters for RAS and aquaculture — high surface-area media, stable nitrification, removes ammonia. Custom sizing, factory-direct from SIGMA. Request a quote.
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UV Filter
UV sterilizers for aquaculture & RAS — kill bacteria, parasites & algae spores, prevent disease without chemicals. Multiple flow rates, factory-direct from SIGMA. Get a quote.
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Dissolved oxygen cone
Oxygen / Speece cones that dissolve pure O2 for high-density RAS & biofloc farms. High transfer efficiency, multiple capacities. Manufacturer-direct from SIGMA. Request specs & a quote.
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Filter Media
High-surface-area bio filter media (MBBR carriers, bio-balls) for RAS & aquaculture biofilters — fast nitrification, durable. Bulk supply from SIGMA. Request specs & a quote.
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Commercial Sand Filter
High-flow commercial sand filters for aquaculture, RAS & pond water treatment — efficient solids removal, easy backwash. Multiple sizes, factory-direct from SIGMA. Get a quote.
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Screen Filter
Motorized self-cleaning screen filters for aquaculture & RAS — automatic backwash, fine mesh, low maintenance. Multiple sizes, factory-direct from SIGMA. Request specs & pricing.
View details →Get a quote for your RAS system
Share your species, target volume and location. Our aquaculture engineers will size the drum filter, biofilter, skimmer, UV and oxygenation for your project and reply within one business day.
RAS system Request a Quote