FC levels and trichlor


LifeTime Supporter
May 30, 2011
E. Bridgewater, MA
I'm just curious . . . Assuming my pool water has near 0 PPM of CYA, and I chlorinate using trichlor tabs, will that chlorine that is bound with CYA, be stabilized enough to maintain FC levels through a sunny day? I was just wondering, especially when opening a pool, insted of adding CYA I could use trichlor for a while until my CYA reaches the desired numbers.

Thank you


Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
The CYA needs to get to 30 ppm or so in the bulk pool water before it provides protection to the FC from UV.

So no, if you wish to manage your pool using TFP levels, you need to add CYA if your pool water truly has 0 CYA.