I have read the materials sent to me about the hydroflow system, and I
have retrieved the same info from the internet.  None of this
information tells me if this system really works to soften
exceptionally hard water or if it is safe for
pacemakers/defibrillators. I need a complete value judgement as to the
efficacy of this product.

If you are talking about www.hydroflow.com, this appears to me to be
complete pseudoscientific nonsense. This is a device that clamps onto
a pipe and supposedly reduces scale by generating an electric field
within the plumbing system. Their web pages are filled with irrelevant
diagrams, equations, and cool simulations. Please note that their own
claims are inconsistent with any change in water hardness, since they
say:

"HydroFLOW does not change the chemical composition of the water in
any way. It works purely on a physical basis, leaving the water
completely drinkable. Essential minerals are retained in the water.
Unlike water softeners, it is not necessary to provide a separate
untreated drinking supply."

My advice is to steer clear of this quackery.

Dear kottekoe-ga:

Thanks! That is precisely the kind of information I was looking for!
Might you be aware of any other type of system that would not require
salt that might actually work to soften water? I will be happy to fill
in in question box if that is what you need. I will, of course, be
happy to pay an additional ten if that is sufficient for your work.

There are a number of ways to treat water to reduce hardness. The
standard method is an ion exchange process that replaces the Calcium
ions with Sodium. The ion exchange resin is periodically recharged
with salt to replace the Sodium. A very effective technique that
removes the ions altogether is reverse osmosis (RO). There are
inexpensive RO systems available to produce water in small quantities
for drinking. There are also deionization systems that do not replace
the ions with Sodium. I am not an expert, but if you are looking to
reduce the hardness for large quantities of water for washing, the
standard water softeners are probably the best approach. If you want
soft water for a fish aquarium or for cooking and drinking, I suggest
investigating an RO system.

Obviously the writer does not understand the technology being
applied,it is not a water softner,it is a water conditioner-There is
nothing wrong with hard water it is only when subjected to variations
in pressure and temperature that the undesirable effects become
evident i.e.-scale,blocked pipes,staining,blown hot water elements
etc-Hydropath quite simply stops scale formation and resultant side
effects all while still maintaining a potable water supply-If you want
to drink chemically softened water that is your choice also why is
there over 400000 units fitted worldwide with 100% success rate.