A pH value of 5.5 would be ideal for human skin. In the whirlpool, a permanent pH value below 6.0 can lead to corrosion. For people it can come to eye irritations, because our tear liquid has a pH-value between 7 and 7.5. A permanent pH-value above 7.8 can lead to cloudy water and to skin pinching because the skin has a pH-value of 5.5. A pH-value above 8.0 can lead to lime precipitation. This lime can cloud the water and settle in the pipes.