RK2 Fluidised bed sand filters

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