I have had my 30 ft above ground pool for 16 years. I use a D.E. filter and a copper ionization system, so all I have needed to do for 16 years is throw in a gallon of bleach once a week and use baking soda or muriatic acid if needed. I usually have no problems. This year I cannot get my chlorine to remain above 0, even though copper is at required level (can't remember level right now), pH is 7.5 and alkalinity is 70. I have added bleach just about every day.