If you are interested in learning the whys and hows of water treatment, boiler chemistry and preservation through preventive maintenance, PM me.
A non-commercial approach is presented. Enough theory for it to make sense,
mainly, what and how to protect your pride-and-joy, save $ thousands over the years.

I am interested. How can I get more info?

I too would like more info, please.

John,
I was active at Williams Grove from about 1965 to September of 1970, when I went in the Navy. I flagged the rear and learned firing on PRR 643. Later, I ran the steam powered water pumping station with a Kewaunee 60 Hp dryback scotch marine and two duplex pumps. It all gave me a head start as a Machinist's Mate, knowing the basics of steam. I still go back for visits at WGHSEA and I'm a member there as well as at Rough and Tumble, where I'm more involved.

The object is to fill-in the " why ".

So the sales claims by the water treaters either ring true,
or you will be able to see through some unsubstantiated
or unreasonable statements. While all boilers have common
factors in their needs, locomotives have special needs,
due to having air ( oxygen ) laden feedwater, multiple sources,
cold feed ( an injector or surface heater does not remove oxygen ),
hard or acidic water, cold wet layup, etc.

Once you get on a good program, instructions will make sense.

Also, to debunk some common misconceptions and to fill-in
some knowledge gaps on the part of experienced operators.