Chlorine keeps disappearing

[mpetrov]

OK, thanks!
They were also suggesting at the pool store if all this fails to try and hose the filter down in a couple of days in case the filter is clogged up or something. I did find out that my husband did not clean the cartrige before putting it into the pump. It was cleaned before storing after last season and was stored in the garage without a cover and may have collected dust. Would this have mattered for chlorine consumption?

[Watermom]

No. That wouldn't have anything to do with it. Follow the advice I wrote above and you'll get it straightened out. We'll be right here to help with any questions along the way!

[CarlD]

Yes, listen to 'Mom. Your problem is that your water has something that's causing your chlorine to be eaten up. Probably something biological or ammonia.
I THINK a pound of Di-Chlor add about the same as 1.25 gallons of 6% bleach--ball-parking here, but I know it's a little more than a gallon of bleach. One gallon of 6% will add 12ppm of FC to your pool, so the pound of "shock" was probably good but it would have added something like 8-12ppm of CYA to your pool as well. 3 pounds of Di-Chlor shock would probably put your CYA in the 30-40ppm range (when starting from 0 CYA).
Still, go back to basics. Use bleach to raise your FC to 15 and check and adjust it 3x a day until it stops "vanishing".
Since 1 gallon of 6% will add 12ppm of FC, 1 quart will add 3 ppm. You don't need smaller increments than that.

Carl