I have been using Pristine Blue for 3 years. Last summer my husband became ill and could not keep up with the pool maintenance. By the time I thought about the pool it was black. I bought the recommended chemicals but could not get it to clear. So I drained it last fall. If I can get it together enough to set the pool up again, can I change to straight chlorine? I have read something about copper and the liner would retain the cooper. I live in Louisiana, the water level has fluctuated this winter with the rain up to 3 feet, I keep draining it down to a about a foot. Also I run a cartridge filter not a sand filter. Anyone have suggestions or comments?