On 10/12/2017 11:39 AM, Rob Morley wrote:
On Thu, 12 Oct 2017 19:30:27 +0100
Tim Streater wrote:

In article 20171012190713.7bb76b8c@Mars, Rob Morley
wrote:

Neutralises calcium ions somehow so they don't form calcium
carbonate?

If you neutralise them, then:

1) a current must flow, where does that come from?

Dunno, but it's called an electrolytic device ...

2) the now neutral calcium atoms would immediately react with the
water to produce calcium hydroxide and hydrogen. So you're back where
you started: with calcium ions in solution.

Indeed - it's beyond my O-level chemistry to explain, but people seem
to think it works and they're probably not all snake-oil enthusiasts.