Zero Chlorine readings please help!

[tamil]

Thanks for the advice! You are right I am seeing the ph drop. How long do I need to keep the cl level at 25? I have decided I am going to switch to bleach, and totally agree that I have something going on, just not sure what. I know i need to get my level up there, but not sure for how long? From this morning until now my clorine was at a 3 is now down to 1.
Thanks

[mbar]

You can have clear water, and something starting to grow in the water that is using up your chlorine. If you don't get it to shock till it holds overnight, you will battling this for a long time. Get a couple of bottles of bleach and put them in - it may take a lot. Your water is probably clear because you haven't gotten to a big algae outbreak yet. This happened to me a couple of summers ago - it took a really good shocking to get rid of whatever was trying to take hold. Use the bleach calc to see how much you need for your size pool, with your cya level