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A huge range of pumps for household, commercial, agricultural and industrial use

Floating Fountains & Dam Aerators

Floating Fountains and Aerators for Dams, Lakes and Large Ponds

Pond Help & Information

Need a hand working out the right gear for your project? Browse our range of help pages or submit a help request directly to our specialists.

Oase Biosmart Gravity Filters

The Oase Biosmart range of gravity filters are suitable for many domestic ponds. Perfect for Koi or messier fish, these filters have a unique graded sponge system which can be easily cleaned using a bottom flushign valve and built in compression handles. Their large size and superior design allows them to hold very large amounts of organic waste from your pond so they don't need to be cleaned as frequently as other brands.

  • Physically large filters with many individual sponges produce a very high capacity suited to large ponds or koi ponds
  • An Oase Bitron or Vitronic Ultra Violet Clarifier can be matched with and then integrated onto a suitably sized Biosmart if required, to help eliminate suspended microscopic algae (green water)
  • Easy to clean, saving time
  • Advanced design creates perfect environment for nitrifying bacteria to live, reducing ammonia and other toxic substances in your pond
  • High quality German engineering, uv stabilised plastic leads to a long service life
  • The filter sponges are replaceable although they last many years. All spare parts are available
  • Flushing valve to remove waste from the bottom of the filter
  • Can be partially recessed in the ground to make it 1/3 of it's original height making it easier to conceal
  • In-built cleaning level indicator and thermometer
  • Additional oxygen enrichment through special water channelling

Aussie's Observations about  Biosmart Gravity Filters

Budget • Good • Better • Best • Superior

Domestic ponds with heavy fish stocking or koi, or a situation where minimal cleaning and maintanence is required.

Much easier to clean than pressure filters. Simply lift up the hinged lid to open since it is not a pressurised system. Quality is very high.

Large physical size can sometimes be difficult to integrate into your landscape. Filter can be partially recessed to make a lower profile.

Product Price Filter TypeIdeal Flowlitres per hourMin Flowlitres per hourMax Flow L/Hourlitres per hourPond Max Vol (No Fish)litresPond Max Vol (With Fish)litresDimensionsL x W x H (mm)Back Wash SystemUVC FittedUltra violet lamp fitted as standardWarranty YearsCleaning IndicatorCanister Above GroundIf canister buried, how much shows above ground?Foam FiltersBio BallsFor micro-organism growthPower Cord LengthHose Tails SuppliedHose Tails OptionalMax Pump Pressure
Oase Biosmart 36000 Filter Gravity Filter
Gravity700080003600018000767x555x4083YesYesN/A25/32/38mm Inlet 75mm Outlet
Oase Biosmart 18000 Filter Gravity Filter
Gravity50005500180009000382x555x4083YesYesN/A25/32/38mm Inlet, 75mm Outlet

Pond volumes for Biotec filters

Examples below represent the possible pond size when using the specified Oase pumps and UV clarifiers.   Other pumps, or use without UVC will vary capacity.

  18000 36000
When using these Pump / UVC combinations> the listed pond sizes would be possible Aquamax Eco Classic 5500
Vitronic 18w UVC
Aquamax Eco Classic 11500
Vitronic 36w UVC
Near natural garden ponds with plant zones, without fish. - litres 18,000 36,000
Near natural garden ponds with plants and a medium fish stock** - litres 9,000 18,000
Garden ponds and Koi ponds with heavy fish stock *** litres 4,500 9,000
*Near natural garden ponds with plant zones, without fish.
**Near natural garden ponds with plants and a fish stock of up to 1,000 grams per 1,000 litres
*** Garden ponds and Koi ponds with fish stock of 1,000 to 3,000 grams per 1,000 litres

Suitable pumps / UVC's for Biotec filters

Biotec filter

18000 36000
Suitable Oase Bitron UV clarifier for this filter

Bitron C 24W

Vitronic 18W - 36W

Bitron C 24W - 36W

Vitronic 36W - 55W

Suitable Oase pumps** Aquamax Eco Classic
3500, 5500, 8500

Aquamax Eco Classic 3500 to 11500

Aquamax Eco Premium 8000

Suitable - Non Oase pumps Laguna Max-Flo
4000 - 7600
Laguna Max-Flo
4000 - 9000

**Special note, if using a waterfall or a long hose between pump and filter the pump will need to be larger to allow for the reduced flow caused by the head (pumping height, and/or hose length)   If in doubt Fill in one of our e-mail help forms and let us do all the calculations for you. About Biosmart filters
The patented silt disposal system allows quick and easy cleaning of the filter and ensures if used correctly the continued development of micro-organisms.

These filters are generally pump fed filters and multi chamber filters, which do not only mechanically filter out dirt from the pond water but also encourage the colonisation of special micro-organisms for the biological filtration process.