FC vs CYA levels (new setup)


New member
Jun 28, 2020
Setting up my new Intex Saltwater pool. My SWG manual says ideal CYA is 20-40, and ideal FC is 3.0. However, the TFP Chlorine/CYA Chart (Chlorine / CYA Chart - Trouble Free Pool) has very different numbers, citing an ideal FC level of 5 at a CYA level of 70. Almost double what the manual says! Can someone explain to me the reasoning behind this suggestion?

I am having trouble getting my FC level up, even after adding some liquid chlorine. I understand some FC burns off in the sunlight, but is this also true if the pool remains covered? It's had a vinyl cover over it all day.

Is my next step, to raise my CYA level (currently ~40 as I was following the manual), and then supplement with more liquid chlorine?


Gold Supporter
Bronze Supporter
Jun 11, 2018
Verona, MO
Many threads on the cya/FC relationship.
Short layman answer is most of the pool industry is stuck in dark ages about that relationship. Edit. The cya essentially holds FC in reserve. High cya high FC less harsh than low cya high FC.

yes, raise cya to 70. Maybe shoot for 60 first then fine tune. Add enough chlorine to get to proper level.
Salt needs to be in the pool 24-48 hours before starting your swg.
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