[rossb]

I have this pond outside that I wanted to top up with a rain barrel. I wanted the water level to be within 1/2 an inch and needed a relaible cheap way to do this. What I built will work well as an aquarium topper upper also. I am going to add it to my new set up. It uses a toilet float, a separate pail, a small electic pump and a water line connection between the pail and the aquarium (you don't have to drill the aquarium if you use a syphon tube to a small hang on exterior tank).

Basically you drill a hole in the bottom of the pail and mount the toilet float in it (the newer type of float). There are rubber washers included so it won't leak. To the water connections you connect an elevated water source (like a rain barrel). You put the pump in the bottom of the pail and set the pail beside your aquarium. You connect between the pail and the tank at about the high level of the tank and postion the pail so the high water level is at the maximum float height. You then use the pump to move water the pail to the aquarium.

How this works. Think of your toilet. When you flush it all the water drops out, the float drops and opens a valve so the tank fills again. Now imagine if the water level in the aquarium was connect to and the same as the tank level. If the water in your aquarium evaporated and some how could flush the tank when it was too low, the float woud open a value and fill both the tank and the aquarium. When it got to the high level it would shot off. The small pump effectively "flushes" the pail when the water level falls below the pipe connecting the pail and aquarium. The pump removes all the water from the pail and the float opens the valve and fills both the pail and the aquarium to the high water level. Aside from the pump there are no electrical connections and the toilet float mechanism is quite cheap.

This is a bit hard to visualize but i have adiagram is anyone is interested. One day I'll get me a website and post a few pictures. I have used it for two years outside and it has worked well. You just have to make sure that the float doesn't get a lot of crud on it and stops floating.[/img]