Re: "Its the negative charge which bacteria, virus laden parasites among other things grow rapidly- and its the positive offset which kills them or renders them weak."

>- some advise taking probiotics after each session

Actually, Yogurt or Buttermilk is generally recommended but some can not take dairy products making probiotics a reasonable substitute. Not replacing the beneficial bacteria can result in a Candida problem.

>- having zapped twice daily for months I felt no benefit,

Do not forget that you were using the cheapest, least efficient zapper available.
Also, do you mean 2 zappings or 2 sessions of 3 zappings?

>- concerned for the potential damage an electrical current can do to one without fully realising it

I know of customers who have been zapping for as long as 10 years without any negative problems. This does not mean that there can not be any. It strongly depends on zapping correctly and having good instructions. There is a lot of difference between a strip of paper with 7 lines of information and a 20 page instruction manual.

>- I am, however, wary of alternative trends coming and going

Zapping has continually increased in popularity over the last 15 years and most of it is word of mouth. This is not likely with a failed or fraudulent product.

>- zapping is not fairing well in my mind.

I have heard this from a number of users of the ZP zapper. Again, it is cheap and minimally effective.

I am preparing a page to show the difference and will post it soon.

OK, here it is: http://www.paradevices.com/cheap_zapper.html