35-litre gravity pond filter box with built-in 5W UVC clarifier and 4-stage filtration for ponds up to 8,000 litres. Kills green algae, bacteria and viruses with UV light while brush bars, dual-density foam and 2kg ceramic biomedia handle debris and biological waste.
Built-in 5W LED UVC lamp – kills green algae and bacteria
4-stage filtration: brush bars, coarse foam, fine foam, ceramic biomedia
35-litre capacity – ponds up to 8,000L (5,000L with fish)
Gravity-fed design – position above pond level
UVC runs on DC 12V – works with solar battery boxes or mains adapter
A gravity-fed pond filter box with built-in 5W UVC clarifier and 4-stage filtration for ponds up to 8,000 litres. The UV light kills green algae and harmful bacteria as water passes through, while the brush bars, dual-density foam and ceramic biomedia handle debris and biological waste. Place above pond level and let gravity do the rest.
✓ Built-In 5W UVC✓ 4-Stage Filtration✓ Ponds up to 8,000L✓ Kills Green Algae✓ All Media Included
This is the same proven PF-35 filter box with a 5W LED UVC lamp fitted inside. The UV targets the algae that causes green water – the single biggest complaint from pond owners – while the 4-stage mechanical and biological filtration handles everything else.
How UV + Filtration Work Together
UVC Clarification
The built-in 5W LED UVC lamp emits ultraviolet light at 265–315nm wavelength. As water flows past the quartz sleeve, UV radiation destroys the DNA of single-cell green algae, bacteria and viruses – clearing green water at the source.
Kills green algae that causes murky water
Destroys harmful bacteria and viruses
LED UVC lamp – approx. 6,000 hour lifespan
5m cable – connects to any 12V DC power source
4-Stage Mechanical & Biological Filtration
After the UV kills the algae, the filtration stages catch the dead matter and handle debris, sediment and fish waste.
Stage 1: 6 x 30cm brush bars – trap leaves and large debris
Stage 2: Coarse foam (PPI 25) – catches medium particles
Stage 3: Fine foam (PPI 35) – polishes the water
Stage 4: 2kg ceramic biomedia – biological filtration for fish waste
Powering the UVC Lamp
The UVC lamp runs on DC 12V and draws 5W. It connects via the included 5m cable to any 12V power source:
Solar battery box – plug into the light output on any of our MPPT battery controllers (Sunspray SE 1000, SE 2000, 100W Pump, Pro Fountain 3500)
Mains 12V adapter – use a standard DC 12V power supply (not included)
Important: The filter box itself is passive – no electrics needed for filtration. Only the UVC lamp requires power. If you run without power, you still get full 4-stage filtration – just no UV algae control.
Pond Suitability
Pond Size Guide
Up to 8,000 litres without fish
Up to 5,000 litres with light fish stock
For heavier stocking, consider additional filtration
Compatible Pumps
Any solar or mains pond pump up to 5,000 LPH
25mm, 32mm or 38mm hose connection (triple adapter inlet)
50mm gravity return outlet
For solar systems, a battery backup is needed to power the UVC lamp
What’s in the Box
1x PF-35L filter box with built-in UVC lamp housing (35L)
1x 5W LED UVC lamp with 5m power cable
6x Brush filter bars (30cm)
1x Coarse foam filter (PPI 25)
1x Fine foam filter (PPI 35)
4x Ceramic biomedia bags (500g each, 2kg total)
Hose adapters (25/32/38mm inlet)
Not Included
Pond pump (sold separately)
Hose (use standard 25–38mm pond hose)
12V power source for UVC lamp (solar battery box or mains adapter)
Your pump pushes water into the filter box. The built-in UVC lamp kills algae and bacteria, then gravity pulls the water through four filtration stages before it returns to the pond.
UV Clarification
Water enters the filter and passes the 5W UVC lamp
UV light at 265–315nm destroys algae DNA on contact
Also kills harmful bacteria and viruses
LED lamp lasts approx. 6,000 hours
Mechanical Filtration
Brush bars catch leaves, string algae and large debris
Coarse foam (PPI 25) traps medium particles
Fine foam (PPI 35) polishes the water
Dead algae from UV treatment is caught by the foam
Biological Filtration
2kg of ceramic biomedia provides massive surface area
Beneficial bacteria colonise the ceramic over 4–6 weeks
Bacteria convert harmful ammonia and nitrite from fish waste
Essential for ponds with fish
Clean Water Out
Crystal clear water exits through the 50mm gravity outlet
Returns to the pond via hose or waterfall spillway
UV + filtration together give the clearest results
