I need help ,possible in programing logic, such as a calk reactor.

I'm using a liter meter 3 to do water changes by dumping the tank water down the drain, the liter meter does this up to a max of 25gall a day spread out 150 times in a 24 hour period. I'm running mine at 10 gpd. I have another slave liter meter pump controlled by salinity probe, set is 53 and the pump is turned on if the salinity drops .5. The main pump dumps salt water down the drain, if the water level fall enough through evaporation or water change the ATO kicks in filling the sump. If the salinity drops the slave pump dumps concentrated salt make up to keep the salinity at target value. While the salt pumps is on the sump level is not affected as the inlet of the pump is in the sump pumping through a 5 gallon container with salt mix slurry and that has a plumbing elbow that directs super saturated salt back into sump. This all works well and is based off of The Dialiseas with out the dialysis membranes, too wastefully of DI water.

I need to be able to program the profilux 3ex so that as a safety measure if the salinity probe measures a low salinity level of say 51, IE an empty salt bucket then the socket powering the slave pump and water change pump will be turned off preventing further dilution of the system. Water change pump is socket 1 and slave is socket 2.

The system as is, has been operating for two weeks flawlessly but I need to add this safety measure as a precaution.