Pool Math App FC levels for SWG differ from CYA/FC Chart


Well-known member
Sep 2, 2010
Montreal, QC, Canada
If you refer to CYA/FC SWG chart on the Troublefree site

FC on the chart has a range of between 3-5.

On the Pool Math application, the recommended range on the log page for FC using a SWG and a CYA of 70 shows a target range of between 3 and 10.

Which is the right one? I’m assuming the chart. Can the app be updated to reflect that?


Gold Supporter
LifeTime Supporter
TFP Guide
Jul 3, 2013
Southern OK
Pool Size
Salt Water Generator
SWG Type
CircuPool SJ-40
3 is the very minimum and you should never get to 3 FC, you should be targeting 5 FC or above to stay algae free... I keep mine between 6 and 7 FC at all times... You can go up to 10 and sometimes I do if I have my solar cover on and the FC does not get used as much..

I am down here in Oklahoma where UV kills my FC faster than you, I have my CYA at 80.. :)


Gold Supporter
May 20, 2020
Katy TX
Pool Size
Liquid Chlorine
We can ask @Leebo to confirm but the "target" is usually a range and not a specific number with the upper part of "target" is 15% of CYA value (approximately). So I think the that is how Pool Math puts in the target ranges.
On the CYA chart for CYA of 70 the 3 is the absolute minimum and the low range of the target is 5 with the high range of target calculated at 10 (15% of CYA 70). So the overall acceptable range is 3 to 10ppm but the ideal range is 5-10ppm.
FYI - the next higher value is SLAM which is 40% of CYA value. You can actually swim with FC up to SLAM value.
Hope this helps and others can provide their thoughts.
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