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Since this was another neighbor down the road, not only did I rinse and pre rinse, but I had to rinse a 2nd time due to what appeared to be some light colored "residue like" streaking left from the SH mix and the first rinse.  All the algae streaks were removed after the first and only application, so the mix was strong enough.  So, instead of a follow up to clean some algae streaks, I went back to rinse more residue.   With post rain storm, it would have looked better, quicker, with less effort.  But, looks good now.....