Quote Originally Posted by mjsboone View Post
Well, this morning brings zip zero chlorine. I want to say that I could see a tinge of yellow in the test bottle, but not enough to register on the lowest level of the vial.
Overnight chlorine loss almost certainly indicates that there is something in the water that the chlorine is oxidizing. The only solution to this is to chlorinate till it's gone OR to drain and refill. (Remember, most inground pools cannot be drained safely without special precautions). You can do the bucket demand test to see how much chlorine it's likely to require: http://pool9.net/bucket-demand/

Unfortunately, we can't tell you WHAT is in the water. We'd know a little more, if you had the K2006. I can tell you that your problem originated in one of two ways: EITHER, it's something the pool store has been selling you -- and yes, stores sell MANY worse-than-useless products -- OR it's partially degraded stabilizer (cyanuric acid), resulting from a period of biofilm (bacterial slime) activity in your pool.