The Ph range matters because certain liquids are corrosive and the pump will not last as long in some environments. For example, the Ph value of salt water is different from that of clean water. This will be detrimental to the life of the pump. To get around this you could use a different type of pump – for example, a stainless steel one, or change the materials of the pump such as the seals. You can also use zinc anodes which will prolong the life of the pump.