patents for scalewatcher
someone asked for the patents on the easywater.
The patents for scalewater are easy to find. Just search uspto.gov and seach for by inventer name:
their website (stopwaterscale.com) says 4, but I could only find 2. The other two may be under a different name. If you search for De Baat Doelman in all fields it comes up with about 30 results. so it's probably in one of them.
also patents are good for 20 years, and since his first was in 1988, that's why you are seeing others come out with this type of device. his early patents are expiring/have expired. (but he probably has new ones too.)
Also some people have said "wrap a wire around a pipe" and one person says "2 inches." That's not accurate. The easywater and the scalewather both have several inches of windings around the pipe.