Filtreau Excellent Bio Drum 35 Gravity-Fed

Building a gravity system with bottom drains? The Filtreau “Excellent” Bio Drum 35 — Gravity-fed (FS851)combines automated drum filtration with a biological stage in one unit, keeping solids out and bio performance high.

Part of the Filtreau “Excellent” Bio Drum range.

Why it’s a strong choice

• Gravity-fed design — ideal for bottom drain installations
• Integrated drum filtration and bio chamber
• Built-in UNOX UV-C module for water clarity
• Multiple 110 mm inlets and outlets for high-flow systems
• Self-cleaning drum screen with automatic rinse cycle

Mechanical stage

Filtreau drum systems use a fine screen that rotates and rinses automatically when blocked, flushing waste to drain. This keeps water levels stable and reduces manual cleaning.

Other Filtreau drum filters in the range use 70-micron INOX screens with automatic cleaning mode .

Specifications

Fit notes — gravity setup

• Install at pond water level for gravity flow from bottom drains.
• Use 110 mm pressure pipework to maintain unrestricted flow.
• Ensure a suitable waste connection for automatic rinse discharge.

Typical flow path:

Bottom drain → Bio Drum 35 → Pump chamber → Return to pond

Maintenance

• The drum screen self-cleans automatically when triggered.
• Inspect spray nozzles and waste chute periodically.
• Replace UV-C lamp in line with manufacturer guidance.

Safety first

• Isolate power before servicing the drum or UV-C.
• Shield eyes and skin from UV-C exposure.
• Ensure waste outlet is securely plumbed to drain.

If you’re building a serious gravity-fed koi system, the Bio Drum 35 gives you automated mechanical filtration with integrated biological capacity in one solid unit.