Is the the basic concept of an auto top-off...

[Sea_Dawg]

I was kinda confused on the whole thing but I think I have it...

There is a container filled with water. It has airline tubing to the tank. There is also another piece of airline tubing in the container conected to an air pump. So when the water gets to a certain level it turns on the air pump forcing water into the tank.

Is this right?

 

[reefman23]

Exactly...for all those who are no familiar with what you are talking about, here is a link... http://www.nano-reef.com/forums/index.p ... opic=29093

These things work great and I plan on incorporating a 1 gal unit in my 20L.

Jesse