Would the level of ppm have any bearing on it's effectivenss on whether it
is a virus or bacteria?
I've heard another forum that the higher the ppm is, the less effective it
is on a virus but more effective on bacteria.
Is there any truth to this?  So some are preferring to go with the 10-14 ppm
rather than the 18 ppm.

Thank you for any information you can provide.