35-litre gravity pond filter box with 4-stage filtration for ponds up to 8,000 litres. All media included – brush bars, dual-density foam and 2kg ceramic biomedia. Works with any solar or mains pump up to 5,000 LPH.
4-stage filtration: brush bars, coarse foam, fine foam, ceramic biomedia
35-litre capacity – ponds up to 8,000L (5,000L with fish)
A proper gravity-fed pond filter box with 4-stage filtration for ponds up to 8,000 litres. Place the filter above pond level, pump water up into it, and clean filtered water flows back to the pond by gravity. No electrics in the filter – it works with any pump, solar or mains.
✓ 4-Stage Filtration✓ Ponds up to 8,000L✓ 35 Litre Capacity✓ Works with Any Pump✓ All Media Included
Unlike small bucket filters where the pump sits inside, this is a full-size gravity filter with four distinct filtration stages. Water enters at the top, passes through brush bars, two grades of foam, and ceramic biomedia before returning to the pond crystal clear.
4-Stage Filtration System
Stage 1: Brush Bars
6 x 30cm brush bars trap large debris – leaves, string algae and sediment – before it reaches the finer media. Easy to remove and rinse.
Stage 2: Coarse Foam (PPI 25)
280 x 280 x 70mm mesopore foam catches medium-sized particles that pass through the brushes. Rinse in pond water to preserve beneficial bacteria.
Stage 3: Fine Foam (PPI 35)
280 x 280 x 70mm minipore foam polishes the water by capturing fine suspended particles. The two-stage foam system gives noticeably clearer results than single-foam filters.
Stage 4: Ceramic Biomedia (2kg)
4 bags (500g each) of ceramic biomedia provide a massive surface area for beneficial bacteria to colonise. These bacteria break down ammonia and nitrite from fish waste – essential biological filtration.
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 adding a UV clarifier or running two units
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
Works particularly well with our Sunspray SE 2000 and 100W solar pump systems
Want Even Clearer Water?
The filter box handles debris, suspended particles and biological waste from fish. For green water caused by algae, add a UV clarifier inline between your pump and the filter box. The UV kills the algae, then the filter catches the dead matter – the combination gives the clearest results.
Your pump pushes water up into the filter box. Gravity pulls it through four filtration stages, and clean water flows back to the pond through the 50mm outlet.
Water In
Pump pushes pond water up through the hose into the filter box
Water enters through the 25/32/38mm inlet at the top
Any solar or mains pump works – the filter has no electrics
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, catching suspended solids
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
Filtered water exits through the 50mm gravity outlet
Returns to the pond via hose or waterfall spillway
No pump needed on the return – gravity does the work
