How does TFP account for free chlorine warnings on things?


Well-known member
Jul 29, 2018
So I'm not a chemist, but I know the TFP FC/CYA chart was created and tweaked by those who are chemically inclined. It's been used well and proven to be tried and true. I'm a fan.

That said, if my CYA is 50 and I hold FC at 7 regularly, what credence am I to give all those product warnings I see about free chlorine levels? Some are even printed in bold and capital letters as if you are taking great risk in going over 4 ppm. The 3 examples I can think of off top of my head are:

Trichlor shock bags: Don't go over 4 ppm or risk bodily harm (pretty serious warning)

Dolphin Nautilus: not over 4 ppm I believe

Rheem propane heater: not over 5 ppm or risk equipment damage and warranty invalidation
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TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
NW Ohio
Those numbers assume a pool with zero CYA. Whether a company recognizes the effect CYA has on FC or not, they aren't going to print a table so just the most simple blanket warning they can put on a thing is what gets put on it.