Filtration Systems
Mechanical and biological filtration for hatcheries, nurseries and grow-out.
Overview
Filtration removes solids and dissolved nutrients from culture water. Mechanical filtration (drum, disc, sand, protein skimmers) removes particles; biological filtration (MBBR, fixed-bed) converts ammonia to nitrate.
Where it is used
- RAS grow-out
- Marine hatcheries
- Recirculating shrimp systems
- Ornamental & broodstock facilities
Typical applications
- Solids removal down to 30 µm
- TAN control at high density
- Water clarity for observation and grading
Benefits
- Enables high-density culture
- Reduces disease pressure
- Improves feed conversion
Limitations
- Requires stable operation & alarms
- Biofilter must be seeded and matured
- Pressure loss must be engineered into system head
Typical project sizes: From compact hatchery skids to industrial RAS with hundreds of m³ of biomedia.
Drum vs Sand vs Bead vs Protein Skimmer
| Parameter | Drum filter | Sand filter | Bead filter | Protein skimmer |
|---|---|---|---|---|
| Solids capture (µm) | 40–100 | 20–50 | 5–20 | Dissolved organics |
| Backwash water use | Low (2–5%) | High (5–10%) | Medium | None |
| CAPEX | Medium | Low | Medium | Medium |
| Best for | RAS main filter | Pretreatment | Nurseries, high-solids | Marine RAS |
Buying guide
How to evaluate suppliers
- Sized on peak solids load, not average
- Verify backwash automation and alarm channels
- Prefer stainless or engineered polymer housings
Common purchasing mistakes
- Undersizing biofilter to save CAPEX
- Ignoring dissolved organics (DOC) build-up
- Skipping pilot maturation period
Technical questions to ask
- What is the guaranteed effluent TSS at design load?
- What is the maximum TAN under normal and stress conditions?
- How is biofilter maturation supported at commissioning?
Warranty considerations
- 12 months mechanical
- 5 years housings
Maintenance
- Weekly inspection of mesh and seals
- Quarterly biomedia turnover check
Expansion capability
- Modular biofilter cells
- Bypass loop for cleaning without shutdown
Energy efficiency
- Drum filters low energy; pumps around them dominate cost
Lifecycle
- 10–15 years housings; 3–5 years mesh, seals, bearings
Technical specification checklist
Line-by-line items you should include in a vendor-neutral technical specification. Download as CSV to hand to your engineer or drop straight into the RFQ Builder.
Budget guide
| Project size | Indicative CAPEX | Indicative OPEX |
|---|---|---|
| Hatchery skid | USD 30–120k | USD 0.10–0.20/kg |
| Mid-size RAS (500 t/y) | USD 400k–1.2M | USD 0.30–0.60/kg |
| Large RAS (5,000 t/y) | USD 3–8M | USD 0.40–0.80/kg |
Indicative ranges only. Real budgets depend on site, regulations, redundancy and scope. Use for internal planning — always validate with an engineering study.
Major cost drivers
- Design flow
- Solids load
- Housing material
- Automation level
Optional equipment
- Ozone injection
- Foam fractionation
- Denitrification module
Installation notes
- Pipework and manifold design critical to performance
Operating cost notes
- Backwash water and pump energy
Maintenance reserve
- Budget 3–5% of CAPEX/year
Procurement checklist
- 1Water analysis of source water
- 2Peak feed and biomass load
- 3Redundancy plan
- 4Draft specification with TSS/TAN KPIs
- 5Independent commissioning test
Supplier evaluation matrix
Score each supplier from 0 to 10 on each factor. Weights are pre-set with defensible defaults — override if your context differs.
| Factor | Weight | |||
|---|---|---|---|---|
Guaranteed effluent TSS/TAN | 25 | |||
Materials and corrosion resistance | 15 | |||
Backwash automation | 15 | |||
Local parts availability | 15 | |||
Total 10-year cost | 15 | |||
Warranty | 10 | |||
Lead time | 5 | |||
| Weighted total | 100 | 0.0 | 0.0 | 0.0 |
Decision wizard
Frequently asked questions
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