Here are the details for one of the filters I've seen :
Pressurised Filter - Ideal for Waterfalls
Bioforce easy to hide, compact units for biological and mechanical pond filtration. The pressurisation allows the option of running the water from the filter to the top of a waterfall. For treating ponds of up to 2200 litres capacity
Effective Pressurised Filtration
Water is forced through special density foam. Because the water is pressurised the foam can fill with many more beneficial bacteria without becoming blocked. It is this larger number of bacteria, taking pollutants out of the water, that make Bioforce so effective.
Increased Performance and Less Maintenance
The water is forced through three specially graded foams which catch particles and hold beneficial bacteria all the way through. This increases the performance of the unit and increases the time between cleaning. Bioforce filters can be cleared of sludge without the need for manual cleaning. Just swap round the hoses and turn on the pump for a few seconds.
Filter Specifications:
For ponds up to 2200 Litres (500 Gal)
Max flow rate - 946 Litres (250 Gal)
20mm - 25mm Hose Connection
Recommended Pump: Titan 2000
12"x10" dia
29x25cm dia
Cable length: 5 mts
and another :
2 Year Manufacturer Backed Guarantee
The Fish Mate Gravity BIO pond filter has been designed to create optimal water quality and healthier fish for ponds up to 500 gallons.
Gravity Models feature U.V. tubes positioned over the water, thus eliminating problems of scaling, quartz tube replacement and frost damage associated with conventional U.V. clarifiers.
Includes SUPRA Bio Media
SUPRA bio media rapidly colonizes beneficial bacteria
Combined UV and Biological Filtration for crystal clear purified water
Flip up lid for easy maintenance
Frostproof quartzless U.V. chamber
2 Year Guarantee
Designed and coloured green to blend with natural surroundings
Dimensions: (H x L x W): 18cm x 36cm x 25cm
another:
Hozelock Ecomax 4500 UVC Combi Pond Filter
Ecomax filter combined biological filter and UVC - This is the top model in Hozelock's Eco range.
Brand New & Boxed with Manufacturers 2 Year Guarantee
Hozelock Helpline Available
Highly Efficient Filtration
A technologically advanced and highly efficient mechanical and biological filter for garden ponds up to 9000 litres (2000 gallons).
Advanced Turbulating Ultra Violet Clarifier (UVC)
Water enters the unit and passes close to a UV lamp, separated from it by its quartz sleeve. The UV light makes algae clump together so it can be caught by the foam. In-built 'turbulator' - the flow of water through the UVC, created by the product design, increases the unit's efficiency by even exposure of the water to the UV light and eliminates the possibility of air locks.
Highly Efficient at Breaking Down Harmful Polutants
Water leaves the UV chamber via a venturi, which aerates the water for a high oxygen content. The venturi's position in the filter is very important - the water is oxygenated before it enters the biomedia, which significantly increases the effectiveness and activity of beneficial bacteria. This results in a highly efficient breakdown of harmful pollutants in the water. The water passes though the plastic biomedia where beneficial bacteria cleanse pollutants.
Biological Filtation Performance
The amount of biomedia contained in the filter has been scientifically measured and tested to ensure optimum biological filtration performance and increases in proportion to the size of filter/pond to support a greater number of fish. A fine layer of foam traps any remaining solid particles.
Clear Healthy Water
Clear healthy water then passes back into the pond. A drain is built in to flush out sludge, which collects at the bottom of the filter. The floor of filter is sloped so sludge collects around the drain for easy removal.
Easy Maintenance
Integral carry handles are positioned on the side of the filter to make the filter easy to lift if maintenance is required. Viewing hatch to observe the internal operation of the filter, in particular whether any maintenance is needed.
Filter Specifications:
For ponds up to 9000 Litres
Max flow rate - 2250 Litres
Inlet: 20 / 25 / 32 / 40mm
UV Rating - 8w
Dimensions: 400mm x 430mm x 300mm
Cable length: 5 metres
Maximum Fish Size: 212cm
Recommended Pump: Titan 3000
I see all of these have recommended pumps in the listing so I take it that the filters need some sort of feed??? would this pose a problem too?? please let me know if you have any experience with these..
P.S. Obviously some of the filters above would be far to big but other smaller filters in the ranges are available.. these are just the first examples I came across.
thanks guys
Iain
