Be confident in your purchase we're an Authorized AutoAqua Dealer. How cool is that?!?!? For small aquariums, a stable osmotic balance is important, because they are particularly sensitive to constantly changing salt concentrations. The AutoAqua Smart ATO Nano Aquarium Water Auto Top Off System, which is designed specifically for nano and pico aquariums under 50 gallons, is one of the best choices. Smart ATO nano is beautifully crafted to allow simple installation and silent operation. A strong diaphragm pump and a dual optical sensor are combined in one pack, so there is no wire in the reservoir, which makes your aquarium look neat and safe! In addition, it comes with two essential but clever gadgets -- Prefilter and Anti-Siphon Valve, which can remove the particles in the reservoir, protect the pump and stop waterflow due to forward siphon.