NGRDF30 - 16,500 gal Pond (7,900 GPH) Polypropylene

The NishikigoiRDF Rotary Drum Filter is a self-cleaning mechanical pre-filter that strains solid waste out of your pond water down to 75 microns before it ever reaches your bio-filter. A fine 316 stainless screen wraps a slowly rotating drum; clean water passes through while leaves, string algae, and fish waste stay on the surface. When solids build up, a float switch triggers a spray bar that rinses the screen and flushes the debris to waste automatically. Choose Polypropylene for a heavy-duty homeowner and light-commercial build, or 316 Stainless Steel for full commercial-grade construction. Both share the same drum, screen, and internals, the housing material is the only difference.

Removing solids first is the single biggest upgrade you can make to a koi pond. Once the heavy waste is gone, a downstream bead or bio-filter like the AlphaONE or AlphaNANO stops clogging and can spend its media on dissolved wastes (ammonia and nitrite) instead of trapped sludge. The result is clearer water, healthier fish, and far less hand-cleaning.

How the Drum Filter Works

• Gravity-fed intake. The drum sits between your pond and your pump. Water enters the housing by gravity and passes through the screen from the inside out, so the filter always runs gravity-in, never pump-fed.
• 75-micron screen. The rotating drum is wrapped in a precision 316 stainless mesh that captures solids most filters let through.
• Automatic backwash. A float switch senses when the screen loads up, spins the drum, and fires a spray bar that rinses trapped solids into the waste line, no hands in the water.
• Protects everything downstream. With solids removed first, your pump, UV, and pressurized filters all run cleaner and longer between services.

Choose Your Size

Key Features

• Removes solids down to 75 microns, far finer than a sieve or brush pre-filter
• Self-cleaning: a float-switch-triggered spray bar backwashes the screen automatically
• Choose heavy-duty Polypropylene or full commercial-grade 316 Stainless Steel, same internals either way
• Gravity-fed by design: the drum runs gravity-in, ahead of your pump, then feeds a pressurized AlphaONE or AlphaNANO. It is not a pump-fed pre-filter.
• Greatly reduces maintenance on your pressurized filters and frees them to work primarily as biological filtration
• Ten sizes for ponds from 2,500 to 100,000 gallons

How It Compares

A rotary drum filter is the most thorough mechanical pre-filtration you can add to a koi pond. Where a settling chamber or brush box only slows the water so heavier solids drop out, the NishikigoiRDF actively sieves every gallon to 75 microns and cleans itself. Because the solids never reach them, your pressurized bead filters need far less backwashing and can act primarily as the biological stage of your system. For a compact pressurized pre-filter on smaller builds, the AquaSieve SS is a simpler option.

Frequently Asked Questions

What does a rotary drum filter actually do?
It mechanically strains solid waste, fish waste, leaves, and string algae, out of the water down to 75 microns before that debris can clog your bio-filter or foul your UV. It is the first stage in a clean, low-maintenance pond system.

How does it clean itself?
A float switch monitors the water level inside the drum. As the screen loads with solids the level rises, which triggers the drum to rotate while a spray bar rinses the captured debris off the screen and out to a waste line. No hands in the water and no filter pads to scrub.

Can I pump water into it?
No. The NishikigoiRDF is a gravity-fed filter. Water flows into the drum by gravity, is screened, and then goes to your pump and on to your pressurized filters. It should never be pump-fed.

Polypropylene or Stainless Steel?
The internals are identical, only the housing differs. Polypropylene is the heavy-duty choice for home and light-commercial ponds; 316 Stainless Steel steps up to full commercial-grade construction for the most demanding installations. Pick your material from the Material option above.

Which size do I need?
Match the model's pond-size rating to your pond and make sure your pump flow does not exceed the model's maximum flow. The table above lists both figures for every size.

Do I still need a bio-filter?
Yes. The drum filter handles mechanical filtration (solids). You still need biological filtration for dissolved wastes, and the RDF makes that bio-filter far more effective by keeping solids out of it. It pairs naturally with an AlphaONE or AlphaNANO bead filter.

How does it ship?
By freight only. The carrier calls to schedule an appointment, and someone needs to be present to receive it. Larger sizes are special-order.