In my last column, I concentrated on iron filters that worked well when ferric — or visible — iron was present in the groundwater. Old-style pressure tanks — be they the more or less standard or galvanized, or the dreaded buried tanks — produced a lot of this visible iron in the late 1960s or early ’70s. Then our industry moved to captive air tanks, which are sometimes called bladder tanks. These tanks did away with the problem of water logging and also gave the customer far less rusty water. This was because the water in the tank and the air were completely separated. This, however, created a whole new situation regarding iron filtration.
Our industry was now faced with water that contained ferrous iron, the kind in solution that can’t be seen. Make no mistake: The water from the well still contains this iron, just in a different form. In my own experience, as my father and I began to install more and more captive air tanks, we soon realized that cartridge and silica sand filters that had been so effective in series with the older conventional tanks were now virtually useless.