I just got a pool a couple weeks back and was told by the previous owner to use c-pool . Ive been adding 250ml of chorline a week and using c-pool once a week. My pool for two weeks now is sparkling with very clear water. I also test it every couple of days and the right levels for chorline look good ( a faint yellow that matches the 1.3 area very well) A guy I know also uses c-pool ( www.c-pool.ca ) and he says he dumps like 10 litres (2.5. gallons) of liquid chorline every week and he uses 2 pucks as well. I use one puck at a time. It sounds like im either using way to less or hes using way too much. I dont know, but my pool water looks good. Any thoughts?