You should not put chemicals in the pool while the vacuum is in. Put the chemicals in and give them a chance to work first. Then you can vacuum and backwash the filter as needed.
It's always better to skim and vacuum first, then balance the chemicals
Chlorine
An outdoor pool does not require to much in the way of pool supplies. You will need a net, a vacuum system, and chemicals. Some people like to use a float to put chlorine tablets into.
as soon as you put the water in you can ad chemicals to it
You don't put chemicals in a pool, if someone threw up in a pool, wouldn't someone clean the pool? I mean seriously.
Put a vacuum plate over the top of the leaf basket (usually supplied with the pool) and plug the vacuum hose into it.
put clorine in. let algae sit then sweep it out with a pool vacuum
You want to have the equipment running while adding any chemicals. You will want to wait about an hour after adding algaecide.
Try the link below-
People use salt, bromine, chlorine, and other assorted chemicals
get shock treatment and then chlorine
No the chemicals used to sanatize the water will kill them