Im kindof at a loss. My chlorine is dropping 1.5ppm overnight and around 5 during day. All other levels are perfect. I'm in texas and its very hot but didnt think it should drop that much overnight in a 12k gallon pool. I have a Hayward DE6000 filter which I thiink is overkill for my size pool and after I did a full cleanout it wasnt dropping at all over night but that didnt last long. Its only been a couple of months ago. Am I missing something that could be causing it?