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Again, that is my question.. What is the problem with the 'soft' water? there is obviously mush LESS mineral salts in it then in 'hard' water. Logically it would make sense that whether it is evaporation, heating by the element etc. etc. that 'the more desolved minerals (hard water) present in the water, the harder the 'spa chemicals' to DEIONIZE the water would have to work. Less desolved minerals salts = less spa chemicals and the easier to adjust Ph. Thats just basic chemistry.