1-4 FC Question


Active member
Aug 1, 2019
West Virginia
Newbie here. How is the recommended levels of free chlorine in a pool which from what I’ve read on guess strip bottles etc, 1-4 ppm possible when I’ve read that a typical day burns up around 4 ppm. Wouldn’t that risk you a time frame where your pool would be 0 chlorine or near that and acceptable to algae growth? Is there something I’m not getting or mistaking here? Thanks.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

Most residential pools use 3" Chlorine tabs in a dispenser of some type, which continually adds FC as it is being burned off.. Initially this works great. But each tablet also contains CYA.. While the Chlorine gets consumed by the sun and bather load, the CYA does not. As the CYA level gets higher and higher, the effectiveness of the chlorine is less and less. At some point, the FC level can no longer keep algae out of your pool.

The improper use of chlorine tablets is the main reason most of us found TFP...


Jim R.


Gold Supporter
Bronze Supporter
Jun 11, 2018
Verona, MO
Welcome to TFP!?
I am not an expert so this is a layman's short version.
Here at TFP we balance the FC level to the CYA level. CYA holds CL in reserve and protects from UV. CYA too low and you lose FC quickly. CYA too high then you need high levels of FC.

We set a target CYA so we know what we are dealing with and use liquid chlorine to sanitize, very rarely pucks.

Our target FC is high enough to allow for the daily UV burn off.
With my CYA of 70 I shoot for 5 to 6 allowing for a drop to 3 or so. Depending on sun exposure, swim load etc. When the grandkids have a party, I may add another 2 points a half hour or so before they swim, or afterward if I missed beforehand.