Drum filters that catch solids before they become ammonia.
A rotating micro-screen takes feed and faeces out of the water minutes after they leave the tank, then cleans itself. Below: how to choose the mesh, how we size it, and what to check before you buy any drum filter.
flow range per unit
standard screen, 316L
PP box · stainless sinking
standard units ship
Removes particles. Nothing else.
Faeces and uneaten feed break into fines and release ammonia the longer they stay in the water. A drum filter removes them early, which lowers the load on everything after it. In a 2025 trout trial, systems with drum filters had over 60% less particles, particulate BOD and particulate COD than systems without, and about half the microbial activity in the water ().Aquacultural Engineering, 2025
- faeces, uneaten feed and particles larger than the screenRemoves:
- oxygen demand and the organic load on the biofilterLowers:
- dissolved ammonia, nitrite, CO₂ or dissolved organics. You still need a biofilter, degassing and, in many systems, a protein skimmer.Does not remove:
Four steps, running on their own.
The drum turns only when it needs to. Between backwashes it stands still and filters.
Water enters
Screen holds solids
Backwash cleans
Sludge leaves
Finer is not always better.
Finer mesh catches smaller particles, but it loads up faster, backwashes more often and uses more water, and the same drum carries less flow. Research on trout RAS shows where the returns stop. A 2025 trial found 45 μm gave better water quality than 70 μm, and 30 μm gave no further gain (). An earlier trial of 100, 60 and 20 μm found all three reached similar water quality in long-term operation ().Aquacultural Engineering, 2025Aquacultural Engineering, 2015
Coarser, around 100 μm
Pre-filtration of intake water; low stocking density
Fewer backwashes and more flow per drum, but more fines pass to the biofilter
Around 60–74 μm
Most freshwater grow-out at normal density. Our standard is 74 μm
A balance of capture, flow per drum and backwash water
Around 45 μm
Dense systems, sensitive species, or where fines are a known problem
Better particle removal in recent trials; more backwashing, so the drum or flow is sized for it
Finer, 30 μm and below
Hatcheries and special cases
Little extra gain for grow-out in published trials; much more backwash water
Mesh options vary by model. Tell us your species, density and feed, and we recommend the mesh and confirm which models carry it.
Box or sinking: it depends on your site.
Both use the same screen and backwash. They differ in how they sit in the system.
Self-contained, set on the floor
Frame only, set into a channel
Pick the metal for the salinity.
A PP housing does not corrode. The metal parts do: screen, drum frame, shaft, fasteners and spray bar. Common practice in the industry is to step up the stainless grade as salinity rises.
مياه عذبة
304 stainless is common; 316L for the screen
Standard 316L screen
مياه قليلة الملوحة
316 / 316L stainless
316L screen; frame and fasteners confirmed per order
مياه بحرية
Duplex stainless, or designs that keep metal out of the water
We confirm every wetted metal part against your salinity before quoting
Ask for the material list of the model you are quoting, part by part. If a supplier cannot give you one, that is a warning sign.
Where a drum filter fits, and where it does not.
مرشح الأسطوانة
Particles down to the mesh size
Continuous, automatic, gravity-fed, wide range of sizes
Does not touch dissolved waste
Disc filter
Particles, on a larger screen area
About 3× the screen area of a drum on the same footprint, so it suits very high flows and tight space ()Innovasea
Higher upfront cost, more complex to maintain
Bead filter
Particles, and some biological treatment
Compact for small systems
Pressurised, needs backflushing by hand or timer, limited flow
Settler / swirl separator
Heavy, fast-settling solids
No moving parts, takes load off the drum
Does not catch fine or light particles
مزيل البروتين
Fine particles and dissolved organics
Removes what screens cannot
Works alongside a drum filter, not instead of one
If your flow is better served by another technology, we say so. Most of our systems pair a drum filter with a biofilter, degassing and UV, and add a settler or skimmer where the load calls for it.
Five checks before we name a model.
A drum filter that is too small overflows when feeding peaks. One that is too large costs more and runs half-empty. These are the checks we run.
Peak flow, plus margin
Size on the highest flow the loop will carry, not the daily average. Add the tanks you plan to add later, so the filter is not the first thing you replace when the farm grows.
Solids load from peak feed
A common design assumption is that dry solids produced are about a quarter of the feed fed. Peak daily feed, not average, sets how fast the screen loads up and how often it backwashes.
Mesh size
Finer mesh catches more but loads faster. The mesh and the flow are chosen together, because the same drum carries less flow on a finer screen.
Levels and head loss
Most RAS feed the drum by gravity. We check the water level from tank outlet to drum inlet so the filter never backs water up into the tanks. The layout also needs an overflow, so a blinded screen cannot flood the room; we check it is there.
Service space and sludge
Room to open the cover, reach the spray bar and change screen panels. A drain line sized for backwash flow, going to a sludge tank or treatment, not back into the loop.
A worked example
A farm feeding 500 kg a day at peak produces roughly 125 kg of dry solids a day. With 300 m³/h through the loop, that is about 17 mg/L arriving at the screen. Those two numbers, flow and solids, pick the drum size and estimate how often it will backwash. Illustrative figures, not a quote.
Standard specification.
Model-by-model flow, dimensions, power and connection sizes are in the datasheet. We confirm the model against your flow and solids load before quoting.
نطاق التدفق
10–600 m³/h across the range
10–600 m³/h across the range
الشاشة
74 μm, 316L stainless mesh as standard; other mesh on request
74 μm, 316L stainless mesh as standard; other mesh on request
الهيكل
PP housing with inlet and outlet
Stainless frame, set in a concrete or PP channel
الغسيل العكسي
Automatic, started by water level or timer
Automatic, started by water level or timer
الماء
Fresh, brackish, seawater; metal parts confirmed per order
Fresh, brackish, seawater; metal parts confirmed per order
Voltage
220 / 380 / 110 V
220 / 380 / 110 V
مدة التنفيذ
Standard units 15 days · samples 7 days
Standard units 15 days · samples 7 days
Need the model datasheet?
Tell us your peak flow and water type and we send the datasheet for the model that fits.
Backwash, sludge and what goes wrong.
Backwash frequency follows the solids load: more feed, finer mesh or warmer water means more backwashes. Backwash water and the solids go to a drain line and a sludge tank, not back into the loop. These are the faults operators see most, and what to check.
Water overflows the drum at feeding
Drum undersized for peak flow, or mesh too fine for the load
Peak flow against the model rating; mesh size; whether feeding can be spread out
Backwash runs almost non-stop
Screen blinding with fat or biofilm, or a blocked nozzle
Nozzles; screen condition; clean the screen as the manual describes
Backwash does not start
Level sensor or timer fault, or no power to the pump
Level switch; control cabinet alarms; backwash pump
Water by-passing the screen
Worn seal or a damaged screen panel
Seals and screen panels; replace the panel
Sludge line backs up
Drain line too small or blocked
Drain size against backwash flow; clear the line
We size the drum against the whole loop.
A drum filter bought on its own is sized on a flow someone gave the supplier. We size it together with the tanks, biofilter and oxygen, so the numbers agree.
Our own factory
Drum filters, tanks, skimmers, MBBR, degassing and UV are made in our 12,000 m² factory in Boluo, Huizhou.
Sized on your data
We check peak flow, feed, levels and head loss before we name a model, and send the numbers.
Run before it ships
Every system is run at the factory before packing, with the control cabinet operating the equipment.
OEM from one unit
Neutral packing or your logo, 220, 380 or 110 V. Samples in 7 days, standard units in 15.
Ask for the factory test checklist, certificates and material list for the model you are quoting.
For most freshwater grow-out at normal density, yes. Recent trout research found 45 μm gave better water quality than 70 μm, so for dense systems or species sensitive to fines, a finer mesh is worth considering. It means more backwash water and a larger drum for the same flow. We show you the difference before you choose.
Yes, a biofilter always. A drum filter removes particles only. Ammonia is dissolved and passes straight through. A protein skimmer is worth adding in marine, shrimp and dense systems, where fine particles and dissolved organics build up.
A drum filter suits most farms: lower cost, wide range of sizes, simple maintenance. A disc filter puts about three times the screen area on the same footprint, so it makes sense for very high flows and tight space.
Yes, with the right materials. The PP housing does not corrode. Metal parts in contact with water must be chosen for the salinity: the industry steps up to duplex stainless in seawater. We confirm every wetted part for your water before quoting.
The drum stops turning and the backwash pump stops. Water keeps flowing through the screen until it blinds and the level rises. That is why the layout needs an overflow, so water goes somewhere safe instead of backing up into the tanks. Ask how the control cabinet for your model behaves when power returns.
It depends on the solids reaching the screen, the mesh and the model. We estimate it from your peak daily feed and flow when we size the filter, and give you the figure with the quote.
Most RAS feed the drum by gravity from the tanks, which is gentler on the solids. We check the levels so the drum fits the gravity line. Pumped inlets are possible where the layout needs it.
Yes. The PP box type sits on the floor with no civil works. The sinking type drops into an existing channel. Send photos and levels and we check the fit.
Daily: look at the backwash and the screen. Regularly: check spray nozzles, seals and the drive. Screen panels and seals are wear parts. Our engineers train your staff at commissioning.
Screen panels, seals and spray nozzles are the usual wear parts. Ask for the spare parts list for your model with the quote.
Send peak flow, feed and water type. Get the right model.
We size the drum against your tanks and the rest of the loop, then quote with the datasheet.
- Model, type and mesh recommendation
- Level and head-loss check
- Material list for your water
- Standard units ship in 15 days