Clscea Aquarium Auto Top Off System Water Filler Compensator Blue, 1pcs

I struggled at first. This isn't meant for use in the display, it's best in a AIO tank in the back chamber where the water level is stable. I had it in the display originally and it would not work worth a darn. Then I moved to back chamber and it's kept my aquarium stable for weeks now. Really worth it for a small 5 gallon reef.

This works great on my nano tank. Took a little while to get it adjusted just right. If you have to use the adapter it will probably leak cause there's only a gasket for one side so i used silicone to seal it and no problems (after the silicone dried i can still take it apart on the gasket side to refill bottle). I've had it set up over a week and the salinity/water level in my tank is holding very consistent.

I've bought three of these at this point. They work exactly as advertised and are very good at keeping a constant water level in small tanks where evaporation is your primary nemesis. The tank in my pictures is 2.5 gallons and I was losing about a half inch of water to evaporation every day. To be honest, I'm a lazy fish keeper and i don't want to perform maintenance every day or even every other day. Weekly water changes are fine, but I don't want to take the time to top off manually, and I certainly don't want to pay for an electric ATO and have the wires and plumbing and everything in the way as well, so I really like this product. Not only does it do its job flawlessly, it is also a bulletproof design based on physics. It cannot fail catastrophically like an electric ATO because it doesn't use a solenoid and float valve, it only uses gravity. If the breather port is below the rim of the tank, it is impossible to have an overflow.Evian bottles still work fine (7/1/22) contrary to another user who I wish would edit their review. I use the Evian 1L bottle in all three applications I have, and I've never had a problem. I really hope this helps you choose this as an alternative to a typical ATO.If nothing else, use this as an electricity-free, disaster-proof way of topping up if you're gone for a weekend or something rather than risking a power outage or solenoid failure and being far away while your electric ATO pumps your entire reservoir of water on to your floor and kills your fish.10/10, I will absolutely buy more of these.

Muy buena alternativa para un acuario nano aquí los calores dónde hasta 32° y se evapora vastante agua así me es de mucha ayuda para suministrar el líquido a la pecera de forma semi automatica

Using it on a fluval flex 9 reef aquarium. Works great.