hang on overflow backup idea

[beaker020]

nope, same problem only worse. And Yikes! did you see the price of that? You are paying alot for optical sensors and dosing pump.

Think simpler. A quick google search turned up this for tank mount:
http://autotopoff.com/products/ST1/index.htm
or this for sump mount:
http://autotopoff.com/products/SS1/index.htm

[beaker020]

to prevent cycling you can add the $20 reset switch upgrade. Highly recommended