On Fri, 16 Jul 2010 11:47:33 -0700 (PDT), harry wrote:
It was invented years ago. Its called a float valve.

The float valve is the easy part. The hard part is where to put it so that
it will work.

You can't easily put it in the pool itself, due to wave action and damage
occuring to it from the swimming activity - it needs its own well.

If you have five feet of concrete all around the pool, you have nowhere to
put the float valve, even though it was invented years ago.

You could put the float valve in the skimmer wells but then you have to run
a hose into the skimmer above the concrete.

Basically if you have a concrete perimeter, you're hosed. The float valve
isn't your problem. The problem is how to run the hose w/o being a danger
to the swimmers.