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Alas, Iodine won't stop algae from growing in swimming pools and algaecides look like nasty stuff, I wouldn't want to swim in it."
Yes, thats a problem; a better alternative could be silver / copper rods, together with a little Iodine and borax. But I havent been able to try this yet. If I ever get an outside hot tub I will.
I have been to pools just using Sea Salt , and a quarter of the chlorine used elswhere,. It worked much better for me / my kids. No stingy eyes, no other problems we know of.