I was maintaining a CYA of 50 last year. The pool level was dropped 18" for closing last fall and refilled to operating depth in late April. I assumed my CYA would be at least close to the ballpark but couldn't test since my TF100 kit was depleted of reagent. I ordered a new TF100 a few days ago, recieved it yesterday. I tested the CYA to find that it was so low as to appear to be zero. (Completely clear solution post adding 0013 and transferring to reading vial.) I added 4lbs to a sock in the skimmer yesterday afternoon. I checked this morning and the entire 4lbs had been disolved. I tested a few min ago, hoping to see at least a small increase in CYA. Not the case. It's still reading too low measure. The pool is reacting as if the CYA level is low, high chlorine consumption when the auto cover is opened. I have another 8 lbs ready to go in, but I figured I'd ask what you guys thought before I did so. My main concern is the apparent total lack of a chemical, who's level is supposedly difficult to to decrease outside a water change. Thanks all.