calcium fall out

I opened pool about 3 weeks ago and all looks great. I started using the 3" chlorine tablets and weekly granular shock ever sunday evening. The problem I am experiencing is when i shock on Sundays the following day I have residual laying on bottom of pool. The chlorine level is where they should be the cya is high 104. Any idea why I am having this fall out? My pool supplier says it is the calcium falling out and not dissolving. What do I do it is messy looking after shocking.

Thanks for any help you can offer. Becky


Mod Squad
TFP Expert
Apr 4, 2007
SW Indiana
Are you just throwing the shock in? If so, it's the undissolved shock laying on the bottom of the pool. A bad idea. I hope it's not a liner pool. :shock:


LifeTime Supporter
Platinum Supporter
TFP Expert
May 7, 2007
Silver Spring, MD
What are your water test results? Cal-hypo, a common shock and the only kind that might warrant that comment from the pool store, shouldn't be used when your CH level is already high.


Mod Squad
LifeTime Supporter
Platinum Supporter
TFP Expert
In The Industry
Apr 1, 2007
Sebring, Florida

Welcome to the forum. Why shock at all? How does your water look?

If you can post a set of test results, you may not need to shock. And, even if you do, you can do so with bleach and eliminate the fall out completely.

Read some of the stickies in the header above. My bet is you may not need to shock. You can get control of your pool water, save some money, and enjoy your pool more if you can test your water and then know how to balance it.