SWCG Chlorine Balance Question

[RobbieH]

So I thought I saw this answered before, but couldn't find and and can't remember the answer if I did read it...

When I have CYA of 80 in my salt pool, why does poolcalculator still recommend only 3ppm of FC? That makes me a bit nervous! I'm keeping it at 6 right now, but would not mind lowering if it is safe.

 

[JohnT]

The superchlorination that occurs in the cell makes up for the reduced activity of the chlorine in the water at the higher CYA.

 

[chem geek]

When I have CYA of 80 in my salt pool, why does poolcalculator still recommend only 3ppm of FC?

With a CYA of 80 it recommends 4 ppm FC, not 3. It is consistent with the Chlorine / CYA Chart for SWG pools.