Review on 🐠 4L Aquarium Auto Water Level Filler Controller and Coral Marine Tank Top Off System - Optimized with Siphon Principle for Automatic Water Addition in Aquariums by Brittany Collins

It works really well for the money. I have 30 long open tanks and the daily evaporation is insane. As a result, I can't worry about level fluctuations in my aquarium, which is known to make the situation more stable. I've seen some comments in the reviews about the refill opening being small, but I haven't found this to be a problem. I had a clean spare air hose and just used gravity. It takes a little thought to get it working, but it works the way I showed it in the picture. Yes it's slow but I'm doing other things while it fills up and just keep checking.