Thanks for helping me understand a bit better now.

So, the CH comes from the tap, and as water leaves the pool, from evaporation or splash out, the CH does not leave, it stays. And when I refill the pool, I am adding more CH to the water, making the CH level rise?

I think that's it.

BUT...as I sit here and look through sample numbers. Now I know to take what the pool store says with a grain of salt, and that is why I come here, after I visit the store.

July 2005
CH 30.0 Below Minimum

March 2006
CH 70.0 Below Minimum

July 2006
CH 100.0 Below Minimum

Oct 2006
CH 50.0 Below Minimum

March 2007 (today)
CH 150.0 Below Minimum

From what you told me, I am thinking it will just rise and rise. But by looking at the store numbers, it is a mod podge of up and down.

I am only asking to try and learn.

As for the CYA levels. On the last report, in October, the level was at 10.00, so maybe with the colder months, it did evaporate. I really don't know. I just test and go from there. And alternate seasons, with the inline and bleach.

I was telling someone the other day. I bought this house 5 years ago, and it came with the pool. I knew nothing, and I mean zip, nada about taking care of a pool. I found this site and have read and asked questions. My pool has never been yuck. Now there have been a couple of times, of cloudy water, but always got it back on track, by following recommedations from here.

This is a very knowledgeable group of people.

Thanks for helping me.
Kathy