What's the most effective way to reliably trigger and observe hard water scale buildup at a micro level? We live in an area that's got some really hard water. It's so hard that it kills most of the fish we try to care for in our aquariums and shrimp?... forget it. While this is sad and challenging for aquarium lovers, this constant quest my spouse is on got one of my kids really interested the concept of "hard water." One particular point that I've been struggling with was to figure out how to "see" hard water. They asked me if we could build an apparatus that would show them the build up of the scales more quickly so they could look at it under a microscope and do various experiments.

I'd really like to encourage their curiosity and so I wanted to ask, what options exist to:


trigger buildup (some kind of a "seed" on a glass pipette or...?)
capture or isolate buildup so that it can be observed with a
microscope 
what kind of microscopic resolution would / should be
used to observe this (preferably semi-realtime, perhaps via
stop-motion capture, with a photo/video attachment as it
accumulates)?
You have to find out what kind of hardness is present in your water. Is it permanent hardness or temporary hardness? The latter goes away with boiling. 

The easiest and visual demo for children is to show the behavior of hard water with a soap bar. Soap when added to hard water does not lather very well. Watch the video here:

https://www.youtube.com/watch?v=jDgSohKVLio 

https://www.youtube.com/watch?v=bBYsfEHKYCk

As a control, you would need to buy distilled water. 

Does your electric kettle develop crusts with time?