The subject of using a cartridge filter got my attention due to an infomercial on TV.

Captive air tanks did away with the problem of water logging and also gave the customer far less rusty water than the old-style pressure tanks because the water in the tank and the air were completely separated. This, however, created a whole new situation regarding iron filtration.

Looking at a water map of the U.S. recently, I noticed that most of the Great Lakes states — which include Michigan, Ohio, Indiana, Illinois, Wisconsin and Minnesota, plus the non-Great Lakes state of Iowa — all have groundwater that is classified as very hard.

Two months ago I wrote that in my next column I would write about something a bladder tank won’t do, in my opinion, and that is make up for a weak well or slow pump.

In my last column I wrote that, on occasion, painted steel bladder tanks will rust from the outside in.

As I said in my last column, after years, indeed, of trying to keep air in pressure tanks, our industry figured out that the air was being eaten by the water.

At the end of my last column I said that this chapter would deal with an important step forward; the bladder tank.