Tunze Osmolator 3 Auto Top-Off System – Precision Water Level Control for Fresh & Saltwater Aquariums
Maintain perfect water stability with the Tunze Osmolator 3, a premium auto top-off (ATO) system engineered for accuracy, safety, and long-term reliability. Designed for both freshwater and marine aquariums, this all-in-one solution keeps water levels consistent—helping stabilize salinity, protect equipment, and support the health of your livestock.
Built with German engineering and decades of refinement, the Osmolator 3 delivers plug-and-play simplicity with advanced safety features, making it ideal for both beginner and experienced aquarists.
Key Features
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High-Precision Optical Sensor (±0.5 mm Accuracy)
Advanced optical sensor detects water level with exceptional precision while resisting interference from air bubbles, deposits, and scratches
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Independent Thermal Safety Sensor
Provides 100% overflow protection by automatically shutting off the pump in the event of overfilling
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Consistent Salinity Control
Maintains a stable water level—critical for reef tanks where evaporation can quickly alter salinity
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Plug & Play Installation
All components included (except reservoir). No programming or setup required—factory-set parameters based on years of real-world use
Included High-Performance Pump
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Turbelle® High Jet 5030 Dosing Pump
- Maximum head height: 6.2 m (20.34 ft)
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Dry-run and blockage protection built in
- Quiet operation with true 3-phase sine wave technology
- Designed for long-term, continuous use
Premium Build & Components
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High-Tech Cable System
- Abrasion-resistant, seawater-safe, and impact-resistant
- Does not harden like standard PVC cables
- High-contrast sheathing allows early detection of wear
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German-Made Tubing & Fittings
- Flexible, kink-resistant PU hose
- Microbe- and hydrolysis-resistant
- Corrosion-resistant push-in fitting (¼" BSP to ø6 mm)
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Compact Mounting System
- Magnetic holder for glass up to 15 mm (0.59")
- Tube holder fits edges up to 22 mm (0.87")
- Suitable for sumps, cabinet filters, or display tanks
Ideal For:
- Reef aquariums requiring stable salinity
- Freshwater aquariums with evaporation concerns
- Sump-based or all-in-one aquarium systems
- Hobbyists seeking a reliable, set-and-forget ATO solution
Why Choose the Tunze Osmolator® 3?
The Osmolator 3 stands out as one of the most reliable and precise ATO systems available, combining optical sensing with independent safety controls for unmatched protection. Its plug-and-play design, premium components, and German engineering make it a long-term investment in aquarium stability and peace of mind.
Whether you're running a high-end reef system or a planted freshwater tank, this system ensures your water level—and your aquarium’s balance—remains exactly where it should be.
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