Key benefits Automatic, reliable top-off for aquariums: keeps water level consistent and reduces manual refills. Built-in noise suppression reduces operating sound for quieter use (note: does not eliminate noise completely). Flexible fit and easy setup: works with standard soda/cola bottles as a simple water reservoir and can be trimmed to match your tank thickness and desired water level. What it does and why you need it Prevents overfilling and maintains a steady water line so you avoid stress to fish and plants and reduce maintenance time. Simple bottle-powered design lets you use widely available, standard-thread bottles for a low-cost reservoir solution. Adjustable hose and pressure-tube design let you fine-tune the stop point so the unit adapts to different aquarium setups. Key features Noise suppression device built in to reduce operational noise (not completely silent). Designed for tanks with cylindric wall thicknesses of 5 mm or 6 mm and compatible with walls up to 8 mm thick. Accepts an international-standard cola/soda bottle as the water reservoir (bottle not included). Differential-pressure tube has two usable lengths/positions; the short tube determines the maximum fill level. Hose length is manually adjustable (cut to size) so you can set the water level and routing as needed. How it works (brief, practical) Install the unit on the aquarium rim in the position that matches either 5 mm or 6 mm wall thickness; it can also be used on walls up to 8 mm. Trim the differential-pressure tube ends as needed: one long, one short. The short tube sets the highest waterline. When the short tube is exposed to air (not submerged), the unit allows water to flow from the bottle. When the short tube becomes submerged, the flow stops—preventing overfill. Cut the hose to the desired length to control how much water is delivered and where the bottle reservoir sits. Compatibility and dimensions Tank wall compatibility: 5 mm and 6 mm standard positions; suitable for walls up to 8 mm. Bottle interface: fits international-standard cola/soda bottle threads. Hose and pressure tube: user-trimmed to required length for custom water-level settings. Use scenarios 1) Daily top-off for freshwater or planted aquariums to compensate for evaporation without disturbing livestock or décor. 2) Hands-free refilling during vacations or multi-day absences when you need consistent water levels. 3) Controlled small water changes or slow fills when paired with a standard bottle reservoir for drip-style addition. Practical notes Noise suppression reduces sound but will not eliminate all noise; consider placement and bottle support to minimize vibration. Carefully trim tubes and check fit against your aquarium wall before first use. Use clean, freshwater in the reservoir bottle and secure the bottle in a stable position to avoid spills. This product provides a straightforward, adjustable solution for automatic aquarium refilling compatible with common bottle reservoirs and typical glass thicknesses.