Hi all. this is my first post so please forgive me if I am asking a lot of questions that have been answered many times over in this forum. I have had chlorine demand issues for last couple of years. I have probably spent $5000 on chemicals the last 3 years alone at a very reputable local pool store. I have tried doing all of the right things...we vacuum and clean pool a couple times a week. We take water samples to the aforementioned pool store weekly to maintain balance and add whatever they tell us. The pool gets clear and the PH and ALK is usually in good levels but the FC is always around 0. Just 4 days ago I took a sample in and the PH was 7.4, TC was 5.5 and FC was .6. They had me add 25 lbs of shock which I did. Today the water looks clean(slightly cloudy) but I can see algae starting on shallow end and test strip shows 0 chlorine. I am at wits end. I have heard replacing the water is only way to really cure this problem, but I don't want to do that until I can replace the liner and have bottom resurfaced so big $$$. Is it possible to cure any chlorine demand problem? I have been looking at forum and looks like I will be ordering a new test kit for starters. Any other suggestions??? Thank you!