the way that i have my system arranged is as follows. I place my fresh R/O water in a closet about 5 feet in the air on a shelf. i just place the syphon tube in the top of the tank but make sure it is touching the bottom. next this syphon tube runs down to the Kalk stirrer on the ground. the distinction i have is that the inlet for the R/O water from the R/O storage in the closet to the kalk stirrer is in the BOTTOM of the stirrer, not the top. my top off solution (kalkwasser and R/O water) is then drawn out of the TOP of my kalk stirrer and is under syphon pressure to the
float valve in my sump. so when the level drops, the syphon draws out top off solution from the stirrer which in turn draws in R/O water to keep the stirrer completely filled and under slight pressure. (i had trouble with leaks from the stirrer because of the pressure.) I believe that because the feeding syphon (the R/O water in the closet,) was so much higher in the air than the rest of the system. On the other hand, i dont have to really worry about the syphon for top off ever breaking. therefore i have a constant water level, constant salinity and constant calcium levels all in one easy to set up solution.