Filtreau Excellent Combi Drum 20/25 Low Version – Gravity Fed

Filtreau Excellent Combi Drum 20/25 Low Version – Gravity Fed

Low-profile koi pond filtration with automatic drum cleaning

The Filtreau Excellent Combi 20/25 Low brings the drum, biological sections and UV-C together in a body just 750mm high. It is a useful option when you want a gravity-fed koi pond with automatic waste removal, but a taller combi filter would make the filter house or access hatch awkward.

In this gravity-fed version, water arrives through the pond’s drain and skimmer pipework, with the circulation pump after the filter. It handles up to 25,000 litres per hour and has a maximum koi-pond rating of 25,000 litres. Allow extra capacity for heavy stocking and feeding, and match the media, air supply and actual circulation to the pond you are building.

Three stages, with a different job for each

The 120-micron drum screen removes suspended waste before it reaches the biological sections. As the screen loads with debris, a level sensor starts the cleaning cycle. The drive turns the drum and the internal cleaning pump supplies the spray bar, washing the collected waste into the drain channel. That removes the need for routine manual screen rinsing, although the filter still needs inspection and servicing.

Behind the drum, moving-bed media provides a home for the bacteria that process ammonia and nitrite. Air keeps that media moving and supplies oxygen to the biological stage. A separate Japanese-matting section provides fixed surfaces for further bacterial growth. The two media types are doing a different job from the screen: clear-looking water is not, on its own, evidence that the biological filter is mature.

The built-in 80W high-output UV-C helps control the suspended algae responsible for green water. It does not replace the biological media, remove settled blanketweed or make water-quality testing unnecessary.

Choose the media you want to use

The standard package is supplied without Hel-X or Japanese matting. The 20/25 Low’s listed media options are 100 litres of Hel-X 13 and 2m² of Japanese matting. Keep the moving media in its intended chamber and the mats in their separate section; filling the moving bed with loose matting would defeat the purpose of the design.

Our high-quality Japanese matting is supplied as 1.2m × 1m sheets. Two sheets provide 2.4m² before cutting. They are uncut sheets, not the fitted Filtreau cartridge: measure the chamber and plan the cuts and spacing before installation. See the top-grade Japanese matting and 100-litre Hel-X 13 pack for the separate products.

The FS854MK cartridge-and-media kit is another route when it is available. It is an alternative to buying the equivalent loose media, not something to add on top automatically. Do not put a full media load into service with a heavy fish load on the assumption it is instantly mature: establish the filter gradually and monitor ammonia and nitrite.

What comes with this model

The filter includes its drum and screen, automatic controller, drive motor, internal screen-cleaning pump, built-in 80W UV-C and the fitted air diffusers. The internal cleaning pump is already part of this Excellent model; you do not need the separate T.I.P. wash-pump add-on used with the basic Filtreau drum.

Allow separately for the circulation pump, external air pump, biological media, pipework, valves and waste connection. Choose the external air pump for the airflow required at the installed diffuser depth, allowing for airline losses and any other equipment sharing the supply.

Key specifications

Understanding the electrical load

The 60W drive motor turns the drum during cleaning, while the 800W internal pump feeds the spray bar. These are intermittent cleaning-cycle loads, not an extra 860W running continuously. The 80W UV-C and your separate circulation and air pumps must also be allowed for when planning the supply and running costs. Actual cleaning frequency depends on feeding, debris and water flow; the wash-pump rating alone cannot tell you the filter’s daily electricity use.

Plan the water level before building the filter bay

A low body is helpful for access, but it does not mean the filter can sit at any height. Set it to the operating water level in the model’s installation drawing. Leave room to open the lid fully, remove service parts and reach the waste drain. Establish the inlet and outlet arrangement on the actual model before committing to concrete or a fixed manifold.

Choose the circulation pump by the flow required after pipe friction and lift, rather than its headline maximum. Adequate drain pipework and sensible bends help the gravity supply keep up. Our pipework and valves range includes the components needed to isolate and maintain the installation.

If the pond pump has to push water into a raised filter, compare the pump-fed 20/25 Low instead. The connection method matters more than a small difference in the product name.

Looking after the filter

Check the waste outlet, spray nozzles, water-level sensor and free movement of the media regularly. An unexpected increase in cleaning frequency is a reason to inspect the screen and flow, not simply extend the wash cycle. Isolate the electrical supply before maintenance, and use the model manual for cleaning and servicing. When replacing the UV lamp or quartz, match the Excellent high-output unit: an 80W amalgam replacement for a different Filtreau range is not automatically interchangeable.

Related equipment and advice

• View the full Filtreau range
• Browse Filtreau drum filters
• Read our drum filter guide
• Compare all drum filters
• View Filtreau UV-C units
• Find replacement UV lamps and quartz sleeves