Trickle filter and degassing unit media

Trickle filter degassing media can come in many different shapes and sizes.

A balance between design, packing configuration, water and gas mixing, surface area and void space is important to the overall performance of trickle filter media.

trickle filter degassing media

For biological filtration, trickle filter degassing media with a good void ratio with the highest possible surface area is desired to result in the best gas exchange, oxygenation and nitrification mix. Biological filters that use the trickle tower/trickle filter design simultaneously degas CO2, oxygenate water and convert ammonia to nitrite to nitrate.

For CO2 degassing, a high void space should be the main concern with media design to reduce waste buildup, maximise water flow and optimise gas movement.

In both applications air is commonly force counter current to the water flow to maximise the gas exchange inside the filter or degassing unit.

Degassing units are commonly applied following biological filters such as moving bed biofilters

Blade Balls

Biological trickle filter media

Degassing Rings

High waste load degassing media

Do not dismiss the power and efficiency of a trickle filter.

As long as attention is paid to gas exchange inside the filter, and water distribution, the trickle filter is incredibly efficient as TAN removal and simultaneous degassing.

Degassing is very important in RAS systems for removal of CO2 and other dissolved gases, it is even more important when using submerged filters like Fluid bed sand filters and MBBR’s.

Trickle filters have a wide loading range in both water flow and TAN removal, as TAN levels increase so does TAN removal and so can be very well suited to shock loaded systems.

Trickle filter media can come in various shapes and sizes, commonly pinned bioballs or a variety of other carbonate based medias have been used.

Pure Aquatics’ Blade Balls have a higher surface area per m3 and feature a sufficient void space to allow for simultaneous degassing.

The bladed shape of the balls allows for sufficient shearing of biofilms that get too thick and helps to prevent mulm build up by eliminating the small spaces often present in pinned bioball designs.

As with all biofilter designs, sufficient pre-filtration and removal of solid waste will improve removal rates.

For assistance with sizing and design of trickle filters please contact us and we would be happy to assess your application.

Degassing rings are an established design of degassing media with a high void space and gas exchange capability for the removal of dissolved gases in waste streams.

Degassing rings are often used where high flows and high solids loads are present. Due to their high Void space, open design and lower surface area, they are more resistant to blocking and therefore stay cleaner for longer. They also do not have as high of a pressure drop and therefore more air can be forced through them (either actively or passively) resulting in better gas exchange.

Predominantly used for degassing, with a small capacity for nitrification, degassing rings are a great option for dissolved gas removal where biological filtration is not the primary concern, or biological filtration is already adequately sized within the system.

ProductSize (approx)SSA m2/m3Void Space
Blade Balls 25mm25mmD46084%
Blade Balls 38mm38mmD32587%
Degassing rings 25mm25mm x 25mm17590%
Degassing rings 38mm38mm x38mm15589%

MBBR Media

The design of MBBR Biofilter media elements is only one part of the story in an MBBR filter, or any biofilter for that matter.

Other factors such as dwell time, hydraulic loading rate, air and water distribution, media velocity and oxygen transfer all determine overall effectiveness and removal rate of nitrogeous waste.

There is a lot more involved in designing any biofilter than just throwing in media and aerating it, and this especially true of an MBBR

Pure Aquatics have identified specific removal rates for our media the PA-X1, PA-X3, PA-X5 and HEL-X FLAKE, and have optimised its performance through identifying design parameters in biofilter design.

Although surface area plays a role in removal rates in MBBR’s, it isn’t all that is involved.

Please do not hesitate to contact us with your MBBR or other biofilter requirements.

PAX MBBR Biofilter media elements NOW EVEN HIGHER SURFACE AREA!!!!


Surface Area >1000m2/m3

Size 11mm x 7mm

Through many years of biofilter design an optimisation, Pure Aquatics have identified shortfalls in some MBBR carrier element designs.

Although surface area does play a part, having a high surface area (when considering conventional MBBR carrier element design) it doesn’t necessarily mean it will process more TAN.

Waste buildup and biofilm thickness, especially in a filter solely designed for nitrification is of the greatest importance, and so a balance between surface area, void space, oxygen transfer and water flow across the media surfaces all determine the medias efficiency.

The PAX1 media has a large surface area with a good balance of protected surfaces for maximum biofilm development, whilst still allowing exfoliation of older biofilms by both physical contact with other carriers, and water flushing of the internals of the media.

Together with our MBBR design and construction parameters, Pure Aquatics can optimise MBBR operation for maximum TAN removal and longevity in performance.

To boost your MBBR’s performance, why not also consider the addition of HEL-X FLAKE?


Surface area >600m2/m3

Size 25mm x 10mm

PAX3 offers a larger media with openings large enough to withstand blocking in system that have higher waste loads.

Commonly used where smaller screens block too fast or where more biomass is needed to be retained (wastewater treatment systems)


Surface Area >1300m2/m3

size 24mmD x 5mmPAX5 MBBR media offers a much better surface area compared to medias of a similar diameter. 

Due to the much smaller opening size, reactor design, pre filtration, aeration and mixing must be optimised to ensure thin biofilms on the media are maintained. Pure Aquatics can assist you with the best equipment and design for the task.

This media is best suited to applications where the reactor has larger opening sizes in the outlet screen/strainer but the water is cleaner.



Surface area 5,500m2/m3

Size 30mm x 1mm

Hel-X medias are a powerhouse in MBBR  carrier design, from conventional style carrier elements to trickle filter media and the incredibly high surface area FLAKE, there is a media for every application.

The HEL-X FLAKE boasts a improved surface area of over 5,500m2/m3, with higher TAN than ever before.

The HEL-X company was the first company to develop this type of media carrier, and has invested significant time and resources into research of their flake product, resulting in a cost effective but equally impressive removal performance compared to other high surface area biomedia types.

Pore size, circulation, biofilter design and overall substrate concentration and diffusion across the biofilms determine the removal rates in the system, and this goes hand in hand with surface area. The volume of surface area and pore distribution within and one the carrier element is only one part of the equation, too much porosity, size of pores and not enough cleaning of the media can negatively impact waste removal in some cases.

HEL-X FLAKE can be used solely in a biofilter, or, as we prefer to use the media, as a mix in certain ratios to boost biofilter removals and result in lower effluent concentrations.

As most MBBR’s in Aquaculture are only filled to 50% void volume, HEL-X FLAKE can be deployed to fill the further 10% of the reactor volume (totaling 60%) to boost biofilter TAN removal.

HEL-X FLAKE is available in either a black re-granulate (recycled) product, or a virgin (white) HDPE.

Pure Aquatics represent HEL-X in Australia and New Zealand and distribute on demand other carrier element types from HEL-X should you have a specific requirement.SURFACE AREA LAB TEST HEL-X FLYER REMOVAL CASE STUDY HEL-X FLAKE SPECS PAX1 SPECS 

Moving Bed Biological Filters

Moving bed biological filters, also referred to as moving bed biological reactors or MBBR’s, are ideal biological filters for ammonia and nitrite removal in aquatic systems.

Moving bed biological reactors perform biological filtration in a controlled fashion but constantly keeping biological media in suspension with air, which oxygenates the water around the media and transports oxygen to the biofilm.

This aeration simultaneously strip a portion of CO2 from the culture water, stabilising pH in the reactor and lowering CO2 levels for the culture species.

MBBR’s (Moving Bed Biological Filters) operate at very low head pressures, and commonly under gravity after a drum filter, reducing pumping costs dramatically.

Their main advantage however is biofilm control and self cleaning. Due to the constant aeration, the media exfoliate against one another, removing waste and exfoliating old and inefficient layers of biofilm, keeping the nitrifying bacteria layer thin and young, for maximum ammonia uptake.

The Pure Aquatics Approach

Pure Aquatics have optimised our MBBR design and opperation by:

  • Media choice
  • Control of dwell times
  • Optimising pipe sizes and minimising friction loss
  • Careful control of dimensions and mixing requirements
  • Superior biofilm control through advanced mixing
  • Optimised aeration and circulation through diffuser design and material selection

Media choice

Our standard media we employ in our MBBR filters is the PAX-1 biological carrier, a standard design that is dimensioned for optimal mixing, water flow, water distribution, waste removal and biofilm surface area growth.

PAX-1 has a minimum surface area of 1000m2/m3.

Also available to utilise in our MBBR’s is the Hel-X Flake biological media, the chip/wafer style media was the first of its kind in the world, and Hel-X continue to lead the way in this style of biological filter media design and manufacture.

The 30mm Hel-X flake is over 5000m2/m3.

Hel-X can be applied at up to 100% of the media volume, but is also applied at between 10-30% as well to augment the biological filter capacity.

People wishing to increase their filtration capacity in their MBBR that utilise a 50% fill rate can add this media at 10% of the media volume to increase the filtration to 60%

Dwell Times

Dwell time inside any reactor is critical, MBBR’s being no exception. The lower the dwell time (or higher the flux rate) the less ammonia and nitrite the filter will remove per pass, and could result in higher residual TAN levels in the tank.

Generally speaking, dwell times cant be too high, as long as oxygen levels are maintained and sufficient food (ammonia and nitrite) is supplied to the bacteria, some dwell times in wastewater treatment plants exceed 24-48 hours.

However, to maintain an increased dwell time a larger reactor (and potentially more media) is required, increasing construction and operating costs. Therefore, depending on the chosen effluent TAN level exiting the reactor, increasing the required size of the reactor to improve dwell time may or may not be required.

through careful design of the reactor overall, Pure Aquatics can design an MBBR for optimal dwell times and performance for any application.

Reactor dimensions and mixing requirements

Reactor dimensions influence mixing inside the reaction, pumping requirements for water flow, and injection depth for air flow.

Utilising the specially designed MBBR diffuser assembly and manipulating biological filter dimensions the Pure Aquatics design approach and MBBR filters achieve optimum results for ammonia removal for the target system requirements.

Aeration, mixing and biofilm control

Unless specified by the customer, all of Pure Aquatics MBBR filters utilise our newly developed MBBR diffuser assembly.

In the past, a plumbed hardline manifold of drilled pipe has been used for aeration of a moving bed, with very inefficient aeration and sub par circulation for the amount of air needed.

A variation of this approach is again a plumbed hard line manifold along the bottom of the reactor, but rather than using drilled pipe, membrane diffusers are used, improving circulation and aeration dramatically through the use of smaller bubbles, concentrated into streams spread throughout the reactor evenly.

This approach, although incredibly effective down have 2 downsides, cleaning can sometimes result in technicians unintentionally breaking off diffusers, or when the diffuser finally does fail due to wear, a new diffuser needs to be fitted and possibly plumbing repaired.

This is not only a time consuming process can can also be expensive, requiring either a diver to install the new diffuser, or complete shut down of the filter while repairs are carried out.

Utilising Colorite Aerotube in a specifically designed, self weighted configuration we have solved the above issues by making the diffuser assemblies not only removable for maintenance, but also mobile to allow the best positioning of the aeration and circulation.

By utilising the superior aeration and bubble distribution of colorite aerotube, we have also dramtically improved oxygen transfer, mixing and cleaning in our MBBR’s, whilst making set up, operation, maintenance and servicing easier.

Media Volume litres2003006001000200040006000
Dimensions 700mmD x 1400mmH700mmD x 1800mmH 1100mmD x 1800mmH1300mmD x 2200mmH 1850mmD x 2100mmH2700mmD x 2200mmH 2700mmD x 2660mmH
Flow rate MIN-MAX40-80lpm60-120lpm120-240lpm200-400lpm400-800lpm750-1500lpm1280-2560lpm
TAN Removal gm’s/day @ 0.25mg/L TAN effluent40gm’s TAN (1kg food)60gm’s TAN (1.45kg food)120gm’s TAN (2.9kg food)200gm’s TAN (4.85kg food)400gm’s TAN (9.7kg’s food)780gm’s TAN (19kg’s food)1200gm’s TAN (29kg’s food)
TAN Removal gm’s/day @ 1mg/L TAN effluent120gm’s TAN(3kg’s food)180gm’s TAN (4.35kg food)360gm’s TAN(8.7kg food)600gm’s TAN (14.5kg’s food)1200gm’s TAN (29.1kg’s food)2360gm’s TAN (57kg’s food)3600gm’s TAN (87kg’s food)

Tan Removal based on:

  • PAX1 media
  • 45% protein content
  • Pure Aquatics MBBR design
  • 25 degree Celsius water temperature


RK2 Fluidised sand biofilters

RK2 Fluidised Sand BioFilters utilize continually moving sand in a clear acrylic column to provide large nitrification capacity in a small footprint. These proven bio filters have a distinct advantage over other types of Bio filters as 100% of the media surface area is utilized in the nitrification process. RK2 Fluidised Sand BioFilters are capable of being placed inline in a low pressure system and maintain a constant flow rate with virtually no maintenance.

RK2 Fluidised Sand BioFilters have the ability to pack a huge surface area into a very small footprint. The also provide very high removal rates per pass (especially with smaller sand sizes) and result in very low residual levels of ammonia and nitrite in the system.

As they are not an aerated biofilter, the water exiting them needs to be degassed on order to remove CO2 and reintroduce oxygen to the water before it is processed further and then distributed back to the culture tanks.

RK2 Fluidised Sand BioFilters can be used in either marine or freshwater applications.
Coupled to an Ozone equipped Protein Fractionator, they create a complete Aquatic Life Support System.

Innovation and quality are built into every RK2 Aquatic Life Support product.
Contact Pure Aquatics for specific applications and quotations.

Fluidised Beds Include:
• Sand media
• Check valve and flow pumps with union connectors

Pure Aquatics utilises standard sand sizes for predicted nitrification rates. Sand sizes as low as 0.2mm can be utilised for higher loads and require less flow to fluidise them.

Small sands can be used for higher removal rates of ammonia and nitrite per pass, and potentially high nitrification rates, however biosolids accumulation at the top of the fluidised bed periodically need to be maintained to avoid excess sand loss.

Fluid bed filters lose between 25%-100% of their bed volume per year, periodic replacement of sand is recommended for consistent filtration rates.

Upon startup we recommend marking the operating level of sand when the filter is turned off, and periodic temporary shut down to check the sand levels and top up as necessary.

ModelDiameter x Height CMMedia Capacity Media Height inside filter dryFlow Rate LPMGM’s TAN/day coldwater 15 degreesGM’s TAN/day warmwater 25 degrees
RK10AC-FSF15cmD x 180cmH11L60 CM50 LPM711
RK40AC-FSF20cmD x 230cmH28L90 CM150 LPM1928
RK75AC-FSF25cmD x 230cmH45L90 CM265 LPM3145

X-Flo Protein Skimmers – By RK2

Professional grade protein skimmers for the home aquarium

The most important things to consider when purchasing a protein skimmer are performance, reliability, and durability. The XFLO aquarium protein skimmer combines all the above to deliver one of the most innovative protein skimmers available today!

Don’t be fooled by sleek looks, gimmicky twists, or exaggerated needlewheel performance!

If a protein skimmer looks good and doesn’t perform, how good is it?

RK2 set the bar for protein skimmers in the public aquarium and aquaculture industries and has been the industry standard for over 25 years. Now you too can use what the professionals use! Let’s take a look at what makes the XFLO aquarium protein skimmer stand out from the ever varying protein skimmer designs in today’s market.


  • 6” Diameter Reaction Chamber – allows for proper flow rates and contact times
  • Counter current flow – allows maximum soluble organic removal
  • High Mounted Water Inlet – Stable water level control without the need for weirs – NO FLUCTUATING FOAM LEVELS!
  • Baffle Plates – stabilise the foam head and direct foam towards to the collection cup
  • Pump Not Inside Skimmer – maximum volume for contact time
  • XFLO’s Domed Lid – allows foam to roll away from riser tube and into the collection cup
  • Cleaning the XFLO – Quick, simple, and does not require tools.
  • Flexible Installation – can be installed in or out of the sump
  • Choose Your Own Pump – Pick your preferred brand .
  • Collection Cups – Sealed with a simple o-ring that allows for easy removal
ModelTank sizeAir inputDwell timeFlow rateAir draw
XF6-2.5750-1500LVenturi1 minute7.5lpm/450lph170lph-280lph
XF6-3.51500-2600LVenturi1 minute11lpm/660lph340lph-450lph

Demand a Higher Standard: XFLO Skimmers by RK2

From materials, to research and testing, RK2’s XFLO skimmer was developed and designed with a higher standard in mind.

XFLO is made from the highest quality materials available. Our moulded bases are made from High Density Polyethylene
(HDPE) that doesn’t require gluing or bonding to fabricate. The reaction chamber is made from a single section of acrylic tube. The riser cone, collection cup, and collection cup lid are made from nearly non-breakable polycarbonate material and our Mazzei Air Injector (Venturi model only) is made from highly durable ozone resistant Kynar. This guarantees it will not break down when exposed to ozone.

XFLO has been tested and designed to run at specific levels of air injection. Don’t believe that the more air/bubbles you inject the better the skimmer will perform. The concept of increasing air flow while increasing contact time is scientifically impossible. Too much air, and the reaction chamber only fills with foam, which displaces water and decreases bubble contact time with “dirty” water, along with the true tank turnover rate.


RK2 Systems, Inc., the parent company of XFLO, has been the industry standard for over 25 years in the public aquarium/zoo sectors. We’ve taken their knowledge and applied it to making a protein skimmer designed for the home aquarium.

Made in the USA!
XFLO Skimmers are designed and manufactured in the USA with the highest-quality materials in the industry.


Saltwater Protein Fractionators

RK2 Saltwater Protein Fractionators

RK2 Saltwater Protein Fractionators (also called foam fractionators or protein skimmers) are filtration devices that remove suspended particulates, dissolved organics, proteins and tints. At the same time, protein fractionation lowers bacteria and pathogen concentrations, while saturating the water with oxygen. Traditional water filtration systems, (i.e: pressurized sand filters, bead filters and cartridge filters), remove particulates but are ineffective against dissolved wastes and act as breeding grounds for bacteria and pathogens.

Water that is filtered through traditional filters is constantly sieved through the trapped wastes. Similar to that of a tea bag, this action leaches bacteria, dissolved organics and tints back into the water. The media in the filter functions as a bio-filter, promoting bacteria, which in turn strip out oxygen. Consequently, the discharge from these filters is generally enriched with bacteria and dissolved organics as well as having reduced oxygen concentration.

When using RK2 Saltwater Protein Fractionators, the fractionation filtration process is simple and highly effective. Air, (in some cases ozone as well), are injected into the bottom of the reaction chamber via an ozone resistant venturi injector. The water to be filtered is introduced at the top of the chamber and exits at the bottom. This creates a mass mixing effect, with the water traveling cross current to the air, which is essential for the effective formation of foam. The foam rises through the column and becomes more concentrated as it passes into the upper rise tube. The tube allows for the water to drain back into the tank via gravity, while the concentrated foam is ejected over the top of the riser tube and collected into a waste drain. The upper chamber is automatically washed down with rinse systems that keep the surfaces clean and prevent the foam from drying and inhibiting the ejection process.

How Ozone and Protein Fractionation Works Together

Ozone Injection enhances the fractionation process in a number of ways. Ozone oxidizes various pathogens, from bacteria to viruses. Ozone is extremely effective on organic water tints creating crystal clear water. Ozone also breaks down the structure of larger organic molecules, which facilitates their removal by fractionation. Being a three-part oxygen molecule, ozone dramatically increases oxygen concentration. Ozone in doses appropriate for aquaculture is very safe.

The fractionation and ozone combination is extremely effective in a variety of applications. Grow out tanks and aquaria displays with heavy bio-loads become remarkably cleaner. Clean Systems, such as larval rearing or holding tanks can become crystal clear. Protein fractionation with ozone is excellent for systems with heavy mucous concentrations such as closed or semi open finfish and shellfish holding systems. Other applications include purging systems, grow out systems, effluent treatment as well as influent water treatment for use within partial and full flow thru systems.

The protein fractionation process increases water clarity and oxygen concentration, and also destroys and removes pathogens. Consequently, appetite, stocking densities, feed and growth rates are all enhanced and animal health improved.

Used within aquaculture, live seafood holding as well as most public aquariums worldwide, RK2 Saltwater Protein Fractionators are an essential component within any aquatic life support filtration system. Protein fractionation is effective in seawater, freshwater as well as brackish water systems, within partial or full flow applications. Individual models are available with processing flow rates from 3 to 2000 gallons per minute. For larger flow rate applications, our protein fractionators can be incorporated into any modular system design, thus allowing us to process any system volume where protein fractionation is required.

  • MOLDED HDPE SCREW TOP LID – Allows for easy maintenance access
  • BAFFLE SYSTEM IN TOP CONE – Creates stilling action to maintain foam structure and laminar ejection
  • AUTOMATED DUAL WASH DOWN ASSEMBLIES – Electronic or battery operated control allows simple, unlimited configurations of rinse time and interval cycling
  • CLEAR SIGHT GAUGE – Makes adjusting water level height inside filter simple
  • ACRYLIC & MOLDED HDPE REACTION CHAMBERS – with no tube wall penetrations
  • KYNAR VENTURI INJECTORS – Standard on all units for injection of ozone gas
  • TUNED VENTURI PUMPS – Provide excellent flow to amp draw design
  • MULTIPLE MASS MIXING FEATURES – Unique “charging points” enhance and increase gas – liquid interface
  • 316 STAINLESS STEEL HARDWARE – Made with the highest quality non-corrosive components
ModelFlow RateDiameterVenturi pumpHeightFootprintOperational weightDry Weight
RK10AC35-75 LPM25.4 CM1/6 HP PUMP
230 VAC, 1 PH
215.9 CM38.1 X 91.44 CM124.73 KG45.35 KG
RK25PE75-150 LPM35.56 CM1/6 HP PUMP
230 VAC, 1 PH
215.9 CM61.0 X 76.2 CM199.58 KG46.26 KG
RK50PE170-340 LPM50.8 CM1/2 HP PUMP
230VAC, 1 PH
251.5 CM61.0 X 106.7 CM76.27 KG99.79 KG
RK75PE245-510 LPM60.96 CM1 HP PUMP
230 VAC, 1 PH
259.1 CM61.0 X 106.7 CM635.02 KG106.59 KG
RK75PE-HF375-585LPM60.96 CM1.5 HP PUMP
230 VAC, 1 PH
259.1 CM61.0 X 106.7 CM635.02 KG108.86 KG
RK150PE585-1,150 LPM91.44 CM1.5 HP PUMP
230 VAC, 1 PH
256.5 CM91.4 X 137.2 CM1351.70 KG165.56 KG
RK150PE-HF870-1,300 LPM91.44 CM1.5 HP PUMP
230 VAC, 1 PH
256.5 CM91.4 X 137.2 CM1351.70 KG170.09 KG
RK300PE1,040-2,060 LPM121.92 CM1.5 HP PUMP
230 VAC, 1 PH
279.4 CM121.9 X 167.6 CM2304.24 KG199.58 KG
RK300PE-HF1,550-2,325 LPM121.92 CM2 HP PUMP
230 VAC, 1 PH
279.4 CM121.9 X 167.6 CM2304.24 KG206.38 KG
RK600PE2,210-4,440 LPM152.4 CM(2) 1.5 HP PUMPS
230 VAC, 1 PH
365.8 CM152.4 X 198.1 CM4846.63 KG340.19 KG
RK600PE-HF3,325-4,990 LPM152.4 CM(2) 2 HP PUMPS
230 VAC, 1 PH
3658.8 CM152.4 X 198.1 CM4891.99 KG408.23 KG
RK1000PE4,345-8,695 LPM213.96 CM(4) 1.5 HP PUMPS
230 VAC, 1 PH
365.8 CM233.7 X 289.6 CM9241.94 KG453.59 KG
RK2000PE5,800-11,605 LPM213.96 CM(4) 2 HP PUMPS
230 VAC, 1 PH
426.7 CM233.7 X 289.6 CM11,584.74 KG544.31 KG
* = HF models operate at higher flow rates and reduced contact times
**Pro Series Models are available at an additional cost. Pro Series includes – schedule 80 PVC plumbing, Hayward True Union Ball Valves, Electronic Wash Down Assemblies and bulkhead fittings

Microbial Supplements

Pure Aquatics Bacteria for Microbial Water remediation provide a full spectrum of organisms for biological assimilation of solid and dissolved wastes.

  • Extensive pond based systems
  • RAS
  • Hatchery
  • Nursery
  • Biofloc
  • Wastewater treatment


Micro+ is a blend of several species of gram positive Probiotic bacteria that help to control disease, assimilate waste and biologically clean aquatic environments.

Supplied in a concentrated liquid it can be dosed directly or bloomed out pond side for larger volumes with the addition of a concentrated nutrient solution.

Nitrifying Bacteria

NMI+ is a blend of nitrifying bacteria that been isolated from functioning and stabilised freshwater and saltwater aquatic systems. NMI+ is used to inoculate biofilters quickly and effectively.

Together with a specially formulated nutrient profile, biofilters can now be started effectively  and cultured to a level to replicate the ammonia production of equal to that of the stock to be introduced.

Biological Filters


Biological Filters are the heart of a life support system for closed aquatic culture systems.

There are many types of biological filters available that Pure Aquatics have experience in using, deigning, building and implementing.

Pure Aquatics both manufacture and import a variety of biological filters and filter media suitable for a wide variety of biological loads and applications.

MBBR Filters – Moving bed biological reactors

Moving bed biological reactors (MBBR’S) have become the standard in biological filtration in recirculating aquaculture systems and for good reason.

They are robust, easy to build, inexpensive to operate, require low pumping heads and they control biofilm thickness, ensuring optimum biological performance.

They also simultaneously oxygenate the filter and strip a percentage of CO2 for the system.

Through extensive and ongoing research, experience and development, Pure Aquatics have optimised our MBBR design for high removal, high oxygenation, superior mixing and easy maintenance.

Trickle Filters/degassing units

Trickle filters were a very widely used biological filter in the past and still have their place in aquaculture today.

Trickle filters are flexible, they have a wide hydraulic loading range, oxygenate and degass the water as a function of their opperation, and have a very high ammonia and nitrite consumption rate per m2. Just like all filters, the higher the ammonia and nitrite levels the more the biological filter removes (however effluent concentrations go up), however trickle filters really excel at high ammonia concentrations.

The 0ne thing they do not do is self clean, and clogging can be an issue. Ways to negate this is to filter the water to a fine degree, and/or increase the void space of the media, which also decreases surface area.

They can also be more expensive to operate due to having to pump to elevated heights for operation.

Employed as degassing units under gravity or on low head pumping loops they are very effective, especially for high density culture systems.

Trickle filters are worth considering for biological filters in certain applications and should not be discounted.

Fluid Bed Filters

Fluid bed filters, also called fluid sand filters, fluidised bed filters or fluidised sand filters, pack a huge surface area into a compact area.

Depending on sand choice, surface areas can range from 8000m2/m3 up to and sometimes exceeding 20,000m2/m3.

They operate well in RAS systems but require the water to be quite clean prior to entering the filter due to their susceptibility to blocking or producing thick bio films that result in excess sand loss.

Fluid bed filters lose sand over time as the sand is colonised by bacteria and becomes lighter and floats out of the system.this can be managed by siphoning the top layer, increasing velocity at the top of the vessel etc but is generally a higher maintenance filter than an MBBR.

They may have a high surface area, but removal rates are generally lower per m2 as a fluid bed is a very abrasive environment, ammonia removal per footprint however, is still at the higher end. Pumping and energy requirements is higher compared to some other biological filter options, but they do have their place in biological filtration.

MBBR Filters


Trickle filters/degassing units


Drum Micro Screen Filters

Drum Micro Screen Filters

Drum Micro Screen Filters are the industry standard for pre-filtration, solids and TSS removal in Aquaculture applications. 

Together with our partners, Pure Aquatics offer accurate sizing of drum filters applied to specific applications and TSS levels whilst offering only the best in design and quality.

Trome – Drum Micro Screen Filters

Trome Drum Micro Screen Filters offer a range that suits the smaller end of the market, opening up drum filtration to the smaller operator, quarantine and purging systems and research systems.

Trome build HDPE drum filters that are completely saltwater compatible (also available with freshwater backwash pumps), their ability to construct smaller drum filters opens the technology to smaller application that would otherwise have to utilise filter matt or filter socks.

TM1 – 5,000LPH – 7,500LPH with 60 micron screens

TM2 – 15,000LPH – 20,000LPH with 60 micron screens

TM3 – 30,000LPH – 40,000LPH with 60 micron screens

TM4 – 60,000LPH – 75,000LPH with 60 micron screens

Trome was founded end 2013, inspired by a need in the aquaculture sector.

Drumfilters are used for many years in commercial fish farms where flow rates are multiple times higher. Most drumfilters
on the market are designed for these larger RAS’s. These drumfilters are not suited for smaller and small scale RAS as can be found in research environments, hatcheries etc. Trome aims at these smaller RAS and with the TM1 the advantages of a drumfilter are now in reach of even the smallest RAS.

​The new design, based on 5 years of experience in the field, together with the well thought combination of materials (HDPE,
stainless steel, POM,…) results in a high quality, reliable and price efficient drumfilter that can be used in both freshwater and seawater environments.

​Thanks to our extensive experience in aquaculture and that of our distributors, Trome will gladly advise you to ensure that the drumfilter best suits your needs.

NP Innovation – Drum Micro Screen Filters

Although NP Innovation is a new company, our history is extensive. In fact, the company founders developed much of the microscreen market. Together we can demonstrate unrivalled experience and track record.

It all started in 1984, when CEO Nils-Åke Persson was a consultant engineer, designing solutions for fish farms. However, the available filtration technology wasn’t adequate, and Mr. Persson had a vision for how he could improve it. To make this vision reality he founded Hydrotech, and just a year later his first microscreen filter became an instant success in the fish farm industry. Five years later he released the drumfilter, which became equally successful. In 1995 the company released its next innovation, the game-changing discfilter microscreen, mainly targeting the municipal water treatment market.

Finally, after almost 20 years of successful innovation, Nils-Åke Persson sold his company to the American group US Filter in 2002. Two years later he left the company and his position as CEO.

In 2013, Nils-Åke Persson and his partners returned, founding NP Innovation, and reclaiming their position in the field of microscreen filter development.

NP Innovation’s wide range of Drum Micro Screen Filters and disc filters for larger applications allows Pure Aquatics to cover larger installments.

With models to suit TSS level from <10mg/L to over 50mg/L and drum diameters from 500mm to 2000mm (and up to 10 screen sections), NP Innovation can specify a drum filter for your specific application.

Drum Micro Screen Filters - NP Innovation
Drum Micro Screen Filters - Trome

YSI Aquaculture Continuous Controllers

YSI Aquaculture continuous controllers for water quality and facility control

The YSI Aquaculture continuous controllers range includes the YSI 5200A, 5400 and 5500D. This range allows full monitoring and control of your aquaculture system either recirculating or pond culture.

Additionally the YSI IOEM (input/output expansion module) and the YSI REM (relay expansion module) allow even further customisation.

Furthermore, utilising the IOEM and REM, monitoring of parameters and switching of components is possible with complete flexibility for almost every system design.

The YSI IOEM makes expansion and customisation possible with either 4 input or 8 input options. As a result a central control system of either a 5200A, 5400 or 5500D can include an IOEM module that can be configured and therefore accept either inputs or outputs from 3rd party sensors or control devices such as flow switches, level switches, pressure switches etc.

The additional inputs in the IOEM can be used for temperature, analog (0 to 1.0 VDC, 0 to 5.0 VDC or 4-20 mA) or digital sensors, output can also be used to control devices.

All while being able to be linked back to a SCADA or PLC system.

You can then utilise the REM module to switch the devices you need to control.


The 5200A is the flagship of the continuous monitor range. It is a multiparameter monitor allowing monitoring of pH, conductivity (salinity and TDS also), temperature, pH and ORP. It also has inputs for 0 to 1.0 VDC, 0 to 5.0 VDC or 4-20 mA where 3rd party sensors such as TGP can be utilised.  


The 5400 is a 4 channel DO monitor. It uses galvanic oxygen probes, and has an additional 6 user configurable inputs for 3rd party sensors 0 to 1.0 VDC, 0 to 5.0 VDC or 4-20 mA.  


The 5500D is available as a 1-4 channel DO monitor using optical oxygen probes, and has an additional 6 user configurable inputs for 3rd party sensors 0 to 1.0 VDC, 0 to 5.0 VDC or 4-20 mA.  

YSI Aquaculture continuous controllers – IOEM module and 3rd party sensors

The additional third party probes could be monitoring a range of parameters. Parameters including but not limited to, DO, Conductivity (salinity, TDS), pH, ORP, Temperature, TGP, Turbidity, BOD, Chlorine, TSS and a range of other Ion selective electrodes.

With the flexibility of inputs in the base monitors and the addition of the IOEM and REM modules, monitor and control of your facility is easier than ever before.

Additional Features

This is just the beginning of the features in the YSI continuous monitors. Other features included in the YSI Continuous monitors are:

  • Event timers
  • Feed timers
  • Internal 10 amp relays

The feed timers integrate with YSI’s feedsmart software for monitoring and control of feeding to the system.

All these features contribute to making these monitors incredibly flexible and powerful straight out of the box.

Addionally the power of the Aquamanager software and Aquaveiwer 2 APP allow for control, alarming and data acquisition.

Operators now have the ability to completely monitor and control their facilities with a fully integrated system.

Contact us today to explore the possibilities that YSI continuous monitors can provide.

For more information you can visit the YSI links below: