Been using methods from this site for years with no issues. I have a 12x24 i ground pool with liner and cartridge filter system. Pool is clear, no visable algae. For the last two weeks, i can pour an entire gallon of 12.5% liquid chlorine into pool and in less than 24hrs, my testing brings back no trace of chlorine. Yesterday i added a bottle in evening (tested at 10ppm 1 hr later), covered pool, by noon today it tests zero chlorine. Pool is clean. Stabilzer is in range, pH is in range. Never had this happen b4. No rain in last 5 days.