Pool girl

it really depends on where you live. and what yout total desolved solids are. calcium (if in good balance) would not have an effect because it is linked to the pool chemisty. you have heat and your water evaporates out a lot, then you are constatly replacing water, especially inteh summer time, and your TDS does not increace. but if you are in a place where it doesn't rain or the sun doesn'ty evaporate your water out then you do have to change it about 10 years or so, but it all depends on you TDS level. i think it can go up to 2500 ppm. before it will stop taking shemicals. also if your CYA is high then you would also haev to drain your pool to get that down or youse a chlorien shock that does not have it in there like calcium hypochlorite or liquid chlorine. hope this helps. pluss your filter sand is changes every 3-5 years so it cann't clog your sand filter.