My new saltwater pool has not been in service for almost 2 years. From the beginning, I have to add muriatic acid to control the pH. Right now, I am addition 1/2 to 1 gallon per week. Can someone please tell me why after nearly 2 years pH continues to creep up and I have to add acid every couple of days. I do not understand it. Is something wrong with the plaster? Should this issue be raised if the pool construction company? Thank you.