Helpful Info - Pond Filter Selection Guide - Water Garden


Filter Guide - Filtral Pt1b

Filtral UVC

All-in-one Pond Filters

  • Underwater pond filter with inbuilt UV clarifier.
  • Suitable for ornamental ponds with no fish up to 9,000 litres.
  • Suitable for goldfish ponds up to 4,500 litres.
  • Also Suitable for filtration of water features.
Filter Guide - Filtral Pt1

Why choose the Filtral UVC?

  • Relatively low cost investment and low running costs.
  • Very discreet underwater installation with no hose connections.
  • Clean water outlet can supply a small stream or be fitted with a fountain kit.
  • 4 different types of filter media for good mechanical and bio-filtration.
  • Pump and UV interconnected and all powered via a single power cable.

Why the Filtral UVC may not be right for you…

  • Not suitable for ponds with Koi Carp.
  • Limited to small and medium sized ponds.
  • Requires removal from the pond for cleaning and maintenance.
Filter Guide - Filtoclear Pt1b

FiltoClear & FiltoClear Sets 

Pressurised Filtration Systems

  • Pressurised pond filters with integral UV clarifier.
  • Suitable for ornamental ponds with no fish up to 30,000 litres.
  • Suitable for goldfish ponds up to 15,000 litres.
  • Suitable for Koi Carp ponds up to 7,500 litres.
Filter Guide - Filtoclear Pt1

Why choose the FiltoClear?

  • Flexible installation options, above or below water level.
  • Can be installed at distance from the pond due to flexible hose connections.
  • Filter can be buried and head can be disguised with decorative rock cover.
  • Water outlet can be directed uphill to supply a waterfall or stream.
  • Maintenance is simple and clean thanks to easy-clean foam handle.
  • Dirty water can be directed away from the pond and used to fertilise plants.
  • UV power can be disconnected without affecting the filter operation.

Why the FiltoClear may not be right for you...

  • More powerful filter pump required to maintain pressurised circulation.
Filter Guide - BioSmart Pt1b

BioSmart & BioSmart Sets

Pump-fed Gravity Out Filter Systems

  • Flow-through box filter with gravity outlet.
  • Suitable for ornamental ponds with no fish up to 36,000 litres.
  • Suitable for goldfish ponds up to 18,000 litres.
  • Suitable for Koi Carp ponds up to 9,000 litres.
Filter Guide - BioSmart Pt1

Why choose the BioSmart?

  • Relatively low cost investment for such an efficient filtration system.
  • Can be supplied using low energy filter pump – very economical to run.
  • Flexible UV option – can be fitted with many of the OASE ultraviolet clarifiers.
  • Smaller Biosmart filters 7000 and 16000 feature integral UV clarifiers.
  • Easy to clean via filter foam compression handles and sludge valve handle.
  • Constant temperature monitoring via inbuilt thermometer.

Why the BioSmart may not be right for you...

  • Larger units can be difficult to disguise.
  • Generally situated fairly close to the pond due to rigid gravity return pipe.
  • Can only be partially buried – gravity return pipe must be above water level.
Filter Guide - FiltoMatic Pt1b

FiltoMatic & FiltoMatic Set

Automated Cleaning Pump-fed Gravity out Filters

  • Self-cleaning filters with gravity outlet.
  • Suitable for ornamental ponds with no fish up to 25,000 litres.
  • Suitable for goldfish ponds up to 12,500 litres.
  • Suitable for Koi Carp ponds up to 7,000 litres.
Filter Guide - FiltoMatic Pt1

Why choose the FiltoMatic CWS?

  • Minimal cleaning and maintenance requirement – automatically cleans itself.
  • Power saving cleaning cycles – regularity of cleaning is temperature dictated.
  • Cleaning programs can be set according to waste production in the pond.
  • Comes supplied with integral ultraviolet clarifier suited to pond volume.
  • Intelligent UV light – automatically switches on/off according to temperature.
  • Digital display provides informative detail such as water temperature.
  • Hose connection to waste outlet allows filter waste to be directed away.
  • Filter waste can be directed towards planting beds as this is a rich fertiliser.
  • Compact design allow filter to be partially buried or installed within the pond.
  • Filter head can be disguised using optional rock cover.
  • Falls under OASE ‘Clear Water Systems’ range – guarantees clear water.

Why the FiltoMatic CWS may not be right for you...

  • Costs a little more than the more basic pond filters due to technical features.
  • Requires manual programming – more complex then less technical filters.
Filter Guide - Biotec Screenmatic Pt1b

BioTec ScreenMatic & ScreenMatic Sets

Conveyor Assisted Pump-Fed Gravity Out Filters

  • Automated waste screening flow through filters with gravity outlet.
  • Suitable for ornamental ponds with no fish up to 140,000 litres.
  • Suitable for goldfish ponds up to 70,000 litres.
  • Suitable for Koi Carp ponds up to 35,000 litres.
Filter Guide - Biotec Screenmatic Pt1

Why choose the BioTec ScreenMatic?

  • Capable of processing larger ponds, fish ponds and Koi ponds.
  • 4 different elements of filtration, debris screen, course foam, fine foam and zeolite.
  • Automatic debris screen minimises waste in the filter – low maintenance.
  • Cleaning made easy thanks to waste collection tray and foam squeezing tool.
  • Very low running costs – waste screen motor uses very little energy in cycle.
  • Can be supplied with low energy AquaMax ‘ECO’ filter pump.
  • Can be directly connected to the OASE Bitron UV clarifiers.

Why the BioTec ScreenMatic may not be right for you...

  • Large filter unit can be harder to hide.
  • Must be installed fairly close to the pond side.
  • Cannot be buried as outlet must be set above water level.
Filter Guide - ProfiClear Pt1b

ProfiClear Premium

Advanced modular Koi pond filtration system

  • Intelligent self-cleaning pond filtration systems.
  • Suitable for ornamental ponds with no fish up to 200,000 litres.
  • Suitable for goldfish ponds up to 100,000 litres.
  • Suitable for Koi Carp ponds up to 45,000 litres.
Filter Guide - ProfiClear Pt1

Why choose the ProfiClear Premium?

  • Capable of filtering very large ponds.
  • Highly efficient, intelligent mechanical and biological filtration.
  • 3 different filter modules each perfectly designed for its purpose.
  • Suitable for either pump fed or gravity fed (bottom drain) installations.
  • Allows for multiple points of inlet for connecting pond skimmers and bottom drains.
  • Removes debris and waste down to 60 micron in size.
  • Recognises when cleaning is required and initiates self cleaning function.
  • Virtually maintenance free - large drum filter takes care of all cleaning and waste discharge.
  • Pumps and UV clarifiers can be stored within end module on gravity fed configurations.
  • Gravity configurations can be secreted below water level, modules flush at ground level.
  • Double row configurations can be used  for filtration of even larger bodies of water.

Why the ProfiClear Premium may not be right for you...

  • Cost - the ProfiClear Premium requires a significant investment as this is high-end filter system.
  • Technology - digital controls and programming may confuse the less technically aware.
  • Pond size - the ProfiClear Premium is better suited to large ponds in excess of 15,000 litres.


Filter Guide - Classic Koi Pt1b

ProfiClear Classic

Modular Filtration Systens for Large Volumes

  • Modular filtration system for large ponds and fish ponds.
  • Suitable for wildlife ponds and swim ponds without fish up to 200,000 litres.
  • Suitable for fish ponds up to 100,000 litres.
Filter Guide - Classic Koi Pt1

Why choose the ProfiClear Classic?

  • Suitable for large ponds with or without fish stock.
  • Flexible installation - can be easily extended to incorporate more modules.
  • Ideal for ponds incorporating a bottom drain feed.
  • Can be installed in either pump fed or gravity fed situations.
  • 4 different filter modules for efficient mechanical and biological filtration.
  • Undertakes all elements of filtration, debris sieving, biological zone and nutrient binding.
  • Easy to maintain using filter media cleaning handles.
  • Coarse debris sieves can be fitted with automatic rotation cleaning motor.
  • Modules can be disguised below ground in gravity feed applications.

Why the ProfiClear Classic may not be right for you...

  • Better suited to Goldfish ponds than Koi ponds.
  • Better suited to larger ponds in excess of 20,000 litres.
  • Cost - high end fish pond filtration that requires some initial investment.
  • Space consumption - linear module configurations consume considerable space.

What is a 'Pressurised' Pond Filter?

A pressurised filter is a 'canister' containing filter media and sponges. The canister is sealed and can therefore be pressurised, meaning water can be forced through the filter and then forced up hill by the pump, if desired.

Benefits & Disadvantages - Pressurised Filters.



  • A pressurised filter can be buried at ground level, allowing the filter to be easily disguised. The filter inlet (from the pump) and the filter outlet should always be set above water level, so that the the water doesn't drain backward throught the filter, should the pump be switched off (or the dirt will flush back into the pond!). We supply a Rock Cover suitable for all Filtoclear Filters, which can be used to disguise the filter lid if desired.
  • As the filter is pressurised, the water can be pushed up hill, perhaps to a waterfall, cascading water blade, watercourse or stream. The water being passed up to the stream has already passed through the filter, so this will be nice and clean.
  • A pressurised filter can be fitted anywhere on dry land, between the pump outlet hose and the discharge point, making it easier to position the filter in a less conspicuous location (perhaps a flower border or at the top of a stream).
  • Pressurised filters can be fitted with flexible hose on both the inlet and outlet side of the filter. This allows the pipework to be laid easily without the need for rigid pipe. If the flexible hose is to be buried below ground, we suggest using our Heavy Duty Flexible Hose.
  • Pressure filters such as the Oase Filtoclear are fitted with an integral UVC (Ultra-Violet Clarifier).



  • Pressurised Filter Systems rely on water being forced to, through, and out of the filter (and possbly up to a higher point). By the very nature of this system, the pump required to combat the additional pressure is likely to be more powerful than a gravity filter would require. On this basis, the power consumption would be greater than a Gravity Filter system.
  • Pressure Filters are generally suited to smaller ponds (up to around 36000 Litres without fish). However, it is possible to use multiple pressure filters to service a larger pond, although this make work out more expensive on running costs and initial purchase costs, over a Gravity Filter System.


What is a 'Gravity' Pond Filter?

A Gravity Filter is usually in the shape of a box, and relies on a pump to force water into the filter box. The water then returns back to the pond using gravity (i.e. the cleaned water flows out of the box in a downhill run). The Filter outlet MUST be above the top of the pond water surface, otherwise the filter box will flood.

Benefits & Disadvantages - Gravity Filters.


  • A gravity filter only needs the pump to pass the water into the box. The pump required to perform this task can therefore be less powerful than a similar pressure filter, so running costs are often substantially less. Bear in mind that a filter should be left running 24 hours per day, 7 days a week, so running costs are an important factor to consider.
  • Gravity filters have a very large filtration surface area so require less frequent cleaning that a similar pressurised filter.
  • Oase Gravity Filters are very easy to clean (for example, the Oase Biosmart Filter Sets , Oase BioSys Screenmatic Sets, Oase Proficlear).
  • The Oase Filtomatic Gravity Filter Sets are self-cleaning, providing a virtually maintenance-free filter system.


  • The outlet pipe must always be above water level (on dry land) so that the clean water can return via gravity. This usually means the filter box is physically above ground level, making this harder to disguise from view.
  • Gravity filter outlet pipes are rigid plastic pipes and bends - not flexible hoses. See Biotec Discharge Pipes & Elbows department.
  • A gravity filter cannot push water uphill after the outlet. If you intend to use the clean outflowing water to provide a stream, then the Gravity filter needs to be positioned at the highest point of the stream (so that the water can begin flowing downhill after the water exits the filter box).


Questions & Answers - Filters & Filter Systems. 


What is the difference between a 'Filter' and a 'Filter Set'?

Filter Sets contain the 3 most important components; a Filter Pump (solids handling pump), UV Clarifier and a Mechanical/Biological Filter. It is also possible to purchase the Filter on its own if desired, assuming you already have a suitable Pump and UVC.

Why do I need a UV Clarifier and what does it do?

An Ultraviolet Clarifier is a very important piece of equipment, if your pond is outdoors and open to daylight/sunlight. A UVC is essentially an ultraviolet bulb mounted in a special housing.

The pond water is pumped through this housing and the UV radiation will kill pathogens (harmful agents that can cause disease) and flocculate ('clump' together) single-celled algae (the cause of green water in a pond). The flocculated algae is then big enough to be trapped by the filter sponges, gradually removing this problem before it spirals out of control. The algae inside the filter is then broken down by the 'friendly' micro-organisms in the filter.


Back to top