I have a Rid-O-Rust siphoning system I use to control rust in my lawn sprinkling system. My well water has a high iron content, thus I use a lot of this product and to save money I have split my watering between zones requiring rust control and those not needing it. My sprinkler system has six zones. It uses Rid-O-Rust on 4 zones and other 2 zones are OK without it. The system controller has two programmable settings. I set Program A for the zones using rust control and Program B for the other t...