"Desmond Wong" wrote in message
...
I know this may be getting too complex, but you could use a small tube,
with
a guide of some sort, styrofoam ball and some sort of plastic "flap" that
would break an infrared beam to let you know that a certain level has been
reached...

I used that in a portable air conditioner to trigger a small timer circuit
to pump the water out of the unit, rather than keep emptying the unit in
the
middle of the night.

I missed the top of the thread so I am adding my 2 cents worth now

Des.



How about just a standard float switch? Ready made, and it's designed
exactly for what the OP wants.

Harry