I will 3rd Jason and Isaac, not worthwhile in most residential outdoor pools.
Just about any "chlorine alternative" is discouraged here. Most of them still require some chlorine, bromine, or baquacil to be used as they are not a true sanitizer. Some provide little to no benefit. Others, like copper-silver mineral systems, can offer some sanitizing but fall far short of chlorine's kill rates and have negative side effects.
I have been around the site long enough to know that if they do someday come out with an alternative that is cost effective and as efficient as chlorine (with numbers backed up with research and real science) that it will be added to the list of recommended sanitizers. Until then, and even after then, chlorine alone provides great sanitization at a low cost with minimal negative effects.