Waterdrop AP431 Replacement Cartridge for Aqua-Pure AP431 Hot Water Scale Inhibitor for AP430SS, Prevent Scale Accumulation and Protect Water Heaters, Pack of 1

There's a whole lotta variables that determine whether these will work for your system requiring a whole lot more water quality chemistry than I ever learned in school (that was a joke), but when you get it right, the calcium carbonate (whitish grey chunky stuff) on your faucets go away like magic . . and these last us nearly a year before that gunk starts coming back . . puttem just within 4' from the input side of the water heater is best for the pipes in your system. Too much use of these can cause premature pipe failure, too little and they don't work, and the pipes clog up . . you oughta consult someone who actually knows what they are talking about before you use, em, or maybe even consult the I-Ching, not sure, but under the right circumstances, like I said, bye bye calcium carbonate . .

Shipped fast and as described, work well

Met expectations

This in my well pump cold inlet line. It is between sediment screen and the house Line input as a second - Post sediment filter. Allows open back flush of the sediment screen. This Cold water inlet filter was added in line to protect the DHW source. Added this household protection from any possible fines in series with a descaling filter at the point of use heater. Extends the flushing cycle on the heat exchanger to once a year. I change this every six months. Put it on subscription delivery and I never forget to change it.

Keeps my on demand water heater clean inside and working like it should. prevents scale from city water

Love it! No dislikes.

I could not find a genuine 3M replacement cartridge on Amazon even though I bought the complete unit here. This seemed to be the cartridge every one was using but I found it not to provide nearly as soft of water as the original 3M made unit. Perhaps it prevents scale buildup but the water is not soft. As I am using it to protect a tankless water heater, I will replace it with the genuine article.

Installed and working great