Key benefits Automatically refills aquarium water to maintain a stable water level and reduce manual topping-up. Compatible with common soda/cola bottles (international standard), so replacement bottles are easy to find. Adjustable for different aquarium glass thicknesses and water-level requirements; provides a simple, low-maintenance solution. Main features and specifications Compatibility: Designed for aquariums with glass/cylinder wall thickness of 5 mm, 6 mm and 8 mm. Bottle connection: Fits standard cola/soda bottles (international standard thread). Adjustable differential-pressure tubes: Supplied tube is cuttable to create a long and a short tube. The short tube determines the maximum water level. Operation principle: Water flows from the bottle until the short tube reaches the water surface; when the short tube is submerged at the set level, the flow stops. Noise control: Built-in noise suppression device reduces refill noise; note that it does not eliminate sound entirely. Hose length: The hose is supplied long so you can trim it manually to the desired length for placement and water-level adjustment. How to use (concise) Select the correct tube length for your aquarium wall: the unit supports two states that correspond to 5 mm and 6 mm glass thickness; it also fits 8 mm walls. Cut the differential-pressure (water) tube at the slanted opening to form one long and one short tube. The short tube sets the highest waterline. Mount the device on the aquarium wall, attach a standard soda/cola bottle, and position the trimmed hose. Water will refill until the short tube is reached and then stop automatically. Adjust hose length by trimming to suit your tank layout. Practical use scenarios Routine evaporation top-up: Keeps water level steady in open-top tanks where daily evaporation is common. Weekend or short-trip support: Maintains water level while you are away, reducing the need for frequent manual refills. Sensitive systems: Useful for planted or reef tanks where a consistent water level helps maintain stable conditions. What to expect Simple installation and manual adjustment for the desired waterline. Reliable, low-tech automatic refilling using standard bottles. Reduced refill noise thanks to the built-in suppression, though some sound may remain. Notes and limitations Noise suppression reduces but does not completely eliminate refill noise. Hose and pressure tube must be manually trimmed to match your aquarium setup. Ensure correct cutting and positioning of the short tube to achieve the intended stop level.