"Swim University" wrote in message
...

Both UV and ozone have bactericidal properties at the time of
application
but do nothing thereafter to protect the water from later addition of
bacteria whereas free chlorine in the water can.

That was the point I was trying to make if I didn't make it clear
Thank you for the back up Clot!

Omitted so far is how frequently the OP drains and (cleans
and) refills his pool. I have no hot tub but our Jacuzzi is
emptied after each use.

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)