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You'll want to shock whether you are using chlorine or bromine. It is possible to shock with a high dose of chlorine, but I reccomend using potassium monopersulfate which is a non-chlorine oxidizer. I think that is what most of the people on the forum use.
Is it necessary to use Cl at all or can I get away with potassium monopersulfate+ozone+spafrog?