>- do typical zappers "sweep" through all the different frequencies to accomplish the job or one single frequency kills most of them?

There are some that sweep but generally, I find that this is not as effective because it takes several minutes at any frequency to be effective.

Generally, the zapper produces a square wave which is composed of harmonics that reach into the higher frequencies and affect parasites.

For a discussion of this, see; Zapper FAQ

well Dr. clarke said:
"Any positively offset [DC] frequency kills all bacteria, viruses and parasites simultaneously given sufficient voltage (5 to 10 volts), duration (seven minutes), and frequency (anything from 10 Hz to 500'000 Hz)."

Thank You all for your responses;
Also, how does the zapper affect red and white cells? they are relatively within size range of some of the stuff the zapper destroy so is it possible that we also kills our defenses (and good bacteria)?
Thank YOu