Category: Filtration systems
Product guide · Mechanical filtrationDrum Filters for Aquaculture — Specs, Sizing & Supplier Quotes
Rotary drum filters are the primary mechanical solids removal stage in almost every RAS and partial-reuse system. This guide covers what they remove, how to size one to your flow and feed load, what separates a cheap unit from a bankable one, and what drives the price — then puts your requirement in front of qualified manufacturers.
What drum filters do
- A rotating drum covered in a fine filter screen (micro-screen) that traps suspended solids as water passes from inside the drum outward.
- Solids build on the screen, the water level rises, a level sensor starts drum rotation and a pressurised spray bar backwashes the captured sludge into a collection tray.
- It is the first treatment stage after the tank outlet: removing faeces and uneaten feed before they break down protects the biofilter, oxygen demand and water clarity.
- Standard on RAS, flow-through polishing and hatchery intake; also used on intensive shrimp and biofloc systems where solids control limits stocking density.
Typical specifications
| Parameter | Typical range | What it means for you |
|---|---|---|
| Screen micron rating | 40–100 µm (60 µm most common) | Finer screens capture more solids but need more backwash water and screen area. |
| Hydraulic capacity per unit | 50–3,000 m³/h | Depends on drum diameter, submergence and micron rating — always confirm at your micron. |
| Backwash water use | 0.2–1.0% of treated flow | Rises sharply with heavy feed loads and finer screens; budget the make-up water. |
| Backwash pressure | 4–8 bar | Dedicated booster pump; low pressure is the top cause of blinded screens. |
| Drive power | 0.25–2.2 kW motor + backwash pump | Filter power is minor next to pumping — head loss across the unit matters more. |
| Head loss | 10–40 cm | Drives the pumping energy penalty for the life of the farm. |
| Materials | GRP, HDPE or 316L stainless housing | 316L for seawater and ozone; GRP/HDPE common in freshwater. |
| Solids removal | 50–90% of TSS above the micron cut | Efficiency drops with fine and fragile particles; long pipe runs shear solids. |
Sizing guidance
Size a drum filter on the hydraulic flow it must pass and the solids load it must remove — not on the tank volume. Always specify capacity at your chosen micron rating and design feed load, and size for peak, not average.
| Project scale | Indicative drum filter duty | Design notes |
|---|---|---|
| Hatchery / nursery, up to 50 m³/h | Single compact unit, 40–60 µm | Low solids load, fine screen for larval water quality; keep a spare screen panel on site. |
| Small grow-out, 100–400 m³/h | One unit at 60 µm | Add a bypass channel so the farm keeps running during screen service. |
| Mid-scale RAS, 400–1,200 m³/h | Two units in parallel | Parallel units give redundancy and let you take one offline without stopping the loop. |
| Large RAS / multi-module, 1,200 m³/h+ | Multiple units per module | Filter per module, not per farm — a single shared filter makes every module share one failure. |
Rule of thumb: required flow (m³/h) ≈ system volume (m³) ÷ target turnover time (h). For RAS grow-out, a 45–60 minute full turnover is a common starting point; add 20–30% headroom for screen blinding, biofouling and future expansion.
How to choose
- Rated at your micron
A unit rated 500 m³/h at 200 µm may only pass 250 m³/h at 60 µm. Insist on capacity curves at the micron you will actually run.
- Screen access and spares
Panel screens replaceable without lifting the drum save days of downtime. Confirm lead time and price of replacement panels before ordering.
- Backwash pump and nozzles
Self-cleaning nozzles, adjustable spray pressure and an accessible strainer — nozzle blockage is the most common field failure.
- Controls and alarms
Level-triggered rotation, high-level alarm, run-time counters and a dry-contact or Modbus output into your farm SCADA.
- Material fit to water
Seawater, ozone or high-salinity biofloc need 316L or fully non-metallic construction; galvanic mistakes surface in year two.
- Sludge handling downstream
The filter only concentrates the problem — plan the sludge thickener, settling or discharge route before the permit review.
What drives the price
- Hydraulic capacity
Price scales roughly with screen area, so with flow and inversely with micron size.
- Housing material
316L stainless typically adds 40–80% over GRP/HDPE on the same duty.
- Micron rating
Finer screens mean more drum area for the same flow — a real cost step, not an option box.
- Controls package
Basic level switch versus full PLC, VFD, remote alarms and SCADA integration.
- Redundancy
Two half-duty units cost more than one full-duty unit but are what lenders and insurers expect.
- Freight and installation
Large drums are volumetric freight; inland transport and crane access can be material on remote sites.
Sourced example: a University of Minnesota RAS feasibility study (2024 figures) budgeted USD 11,000–27,000 per drum filter for designs sending roughly 20–180 m³/h (86–799 US gpm) to the filter, based on an equipment company's estimates, not invoices. Larger multi-unit installations, controls and installation: not sourced. Confirm against at least two comparable quotations.
Common specification mistakes
- Sizing on average flow instead of peak flow, so the filter blinds at feeding time.
- Comparing quotes at different micron ratings — the cheapest unit is usually the coarsest.
- Omitting the backwash booster pump and sludge handling from the budget.
- No bypass or standby unit, so screen maintenance means stopping the whole loop.
- Long, turbulent pipe runs upstream that shear solids into unremovable fines.
Quote checklist for drum filters
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.
- Screen micron rating — your required value, or “unknown”
- Hydraulic capacity per unit — your required value, or “unknown”
- Backwash water use — your required value, or “unknown”
- Backwash pressure — your required value, or “unknown”
- Drive power — your required value, or “unknown”
- Head loss — 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
- RAS biofilters
The biofilter downstream depends on good solids removal
- RAS culture tanks
Tank drain design decides how solids reach the filter
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.
Drum filters — buyer questions
Get quotes for drum filters
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
- An Economic Feasibility Analysis of Food Fish Aquaculture in Minnesota (Tables 16 and 23; figures from 2024 expert interviews) — University of Minnesota, 2025-06
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.