You'd be better off lowering your pool water temperature (or not heating it) and using a large dose of Polyquat 60 algaecide and if you had time to lower phosphates with a phosphate remover then that would also be an option. Low phosphates combined with an algaecide should prevent algae growth even with no chlorine in the water. Though copper ions could also prevent algae growth, they can stain plaster surfaces so would be too risky though in your case you have a vinyl liner -- but you can't easily remove the copper once you've added it so I don't recommend it.