I have a 10 gallon top-off water tank next to my display tank. I use the Tunze Auto-Topoff to maintain proper salinity. I would like to hook up an optical sensor to my Profilux 4 to inform me (alarm, email etc.) that the water level in my top-off tank needs to be refilled. I positioned the sensor at the bottom of the tank but I cannot find programming to enable me to do this. Any help? Thank you.