Why does the TFP app suggest FC at 4 - 8 PPM but CDC recommends 1-3 PPM?

JaceTheAce

Bronze Supporter
Apr 10, 2020
21
Utah
This is my second year using the TFP app to track and balance my pool's chem levels. Last year I used pucks but due to escalating CYA issues I switched this year to liquid bleach. It has been working great but I want to make sure I'm not adding too much chlorine.

Current Levels:
  • FC: 5
  • pH: 7.5
  • TA: 85
  • CH: 250
  • CYA: 45
  • Temp: 90F
Other Key Information
  • I keep the pool covered with a solar cover when not in use
  • I keep the 2-speed pump running on low 24/7 but on high when when the pool is in use
  • The water is sparkling clear and clean and there is zero "slimy" feel anywhere on any of the walls or floor of the vinyl liner
Based on the stats listed above the TFP app is recommending a target FC level of 4.0-8.0. Based on the research I've done most pool "experts", including the CDC, recommend keeping FC levels at 1-3 PPM. Can anyone here explain why the TFP app differs from the CDC and other pool "experts"?
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
23,573
Bedford, TX
J,

CDC recommendations are for public pools where all kinds of really bad stuff can happen.. So they recommend a low CYA level and a corresponding FC of 1-3.. That is just one reason that public pools have that "chlorine" smell.

TFP recommends a higher CYA level and a higher corresponding FC level.

Because of the higher CYA level, the active chlorine in a TFP pool is usually less than the amount of chlorine allowed in drinking water.

Thanks,

Jim R.
 

JaceTheAce

Bronze Supporter
Apr 10, 2020
21
Utah
That explained it perfectly and is exactly what I needed to know. THANK YOU!!
For future reference for anyone else with this question, the TFP page with the CYA vs Chlorine chart is here:
 
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