Should i anticipate daily FC loss by overshooting the recommendation?


Active member
Jul 30, 2016
I have CYA=40

the Pool Math app says my target FC is 5ppm.., the CYA table says 5-7ppm

let's say I choose 6ppm

Should I aim for say 8ppm every morning, knowing I am going to go down a few ppm by the time the sun sets?

If i don't, i will fall below my target - indeed, if i begin the day at my target, i will be below the target pretty early in the day..., I'm worried that being below the target most of the day, every day is going to lead to trouble...

Or.., does the recommended FC level account for daily loss?


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
At 40 CYA, minimum FC is 3. That is the only absolute value in the chart.

You need to determine by testing what level of FC you need to target in order for it not to drop below minimum before you add again. It could be 5, it could be 8. You'll only discover what your pool's target should be by testing. If every day you test and it is 4, you could actually target a little lower and save some bleach. But if you find it's at 2 before you dose, you need to raise it. There are too many variables to set an exact value. Someone with a lot of shade or a cover will lose hardly any, someone with full sun and a lot of kids will use a lot.
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Well-known member
Jun 16, 2019
There are 2 basic schools of thought here. Some folks save every last drop of chlorine after they are above their minimum expected FC levels. Others like a little insurance by going slightly high like you suggested. Its all a personal preference as to what makes you sleep better at night. Like Richard said above, the only hard # is the minumum. Do not touch that.