You'll see the acronym ATO mentioned a lot on the forums. It stands for Auto Top Off. What is an auto top you ask?
An Auto Top Off System automates the addition of water to your saltwater aquarium that is lost due to evaporation.
I have used a couple different ATO's in my time as a hobbyist including a JBJ ATO and a Tunze Osmolator. I currently am using the Tunze version.
The good thing about these systems are the fact that they eliminate an almost daily chore. The problem with these systems are issues that can happen with any equipment we use in our tanks. They get old/used and parts fail.
So what about you? What has been a really good ATO in your experience?