AquaForte UltraSieve III – Max Flow 4,000 GPH
Market-Leading Stainless Steel Sieve Pre-Filter for Koi & Swimming Ponds
 
The AquaForte UltraSieve III is widely regarded as one of the most reliable and efficient pre-filters on the market.
Proven over more than 15 years of continuous use, it is the benchmark mechanical pre-filter for serious koi ponds and swimming ponds where water quality, reliability, and low maintenance are non-negotiable.
Its success lies in a simple, intelligent design with only one moving part, delivering outstanding performance with minimal failure risk.
 
Why UltraSieve III Is the Industry Standard
Market leader for 15+ years
Extremely reliable – only one moving part
True waste removal – debris is completely separated from circulation
Silent operation – no noise, no turbulence
No water loss – closed-loop filtration
Ideal for swimming ponds – hygienic, efficient, predictable
This is mechanical filtration done properly.
 
How the UltraSieve Works (Why It’s So Effective)
Pond water flows into the UltraSieve over a moving weir
The weir is connected to a float, automatically regulating water level
This patented level-control system ensures exact flow balance with the pump
Water passes over a curved stainless steel sieve
The sieve is made from hundreds of triangular stainless steel rods:
Spaced at 200 or 300 microns (0.2–0.3 mm)
Set at a 7° angle
Solid waste remains on the sieve
Clean, sieved water falls through to the main filter
Critically, debris is removed before it can be broken down by the pump, preventing dissolved pollution.
 
True Waste Separation = Better Water Quality
Unlike brushes or foams, UltraSieve filtration:
Removes waste entirely from circulation
Prevents organic breakdown
Reduces ammonia load
Improves biological filter efficiency
Results in clearer, healthier water
Waste can be flushed out and 100% recycled (ideal for garden use).
 
Maintenance (Simple & Fast)
Not self-cleaning – by design
Open the large debris slide valve
Rinse waste away in seconds
Stainless steel sieve never needs replacing
No consumables. No media costs. No complexity.
 
Key Technical Features
Maximum flow: approx. 4,000 GPH
Pump connection:
Supplied with long suction pipe drawing water from beneath the float
Prevents air draw and pump cavitation
Inlets:
2 or 3 × 110 mm gravity inlets
Debris outlet:
Large 90/110 mm outlet with slide valve
Flow control:
Patented automatic level regulation
Housing:
Heavy-duty polypropylene construction
Filter element:
Stainless steel sieve (200 or 300 micron options)
Lid:
Available separately
 
Ideal Applications
Koi ponds
Swimming ponds
High-stock ponds
Large gravity-fed filtration systems
Installations where reliability is critical
 
Bottom Line
The AquaForte UltraSieve III is not just a pre-filter—it is the foundation of a professional pond filtration system. Silent, reliable, consumable-free, and proven over decades, it removes waste properly before it becomes pollution.
If you are building or upgrading a serious koi or swimming pond, this is the correct pre-filter.