Hello.. confused over how to read the chlorine/CYA chart..

[Allison&pauls]

Hello there! I'm very new at this, and have a kind of a 'stupid' question.
On this chlorine/CYA chart I see ...
DO I read it like this -
If I can get my CYA to the target of 30, therefore my target FC will be 4. and to get to the target FC of 4 I need to add enough shock to get the FC level to 12 for a while?

This doesn't exactly made any sense to me.
Can anyone tell me how to read this thing, I'm feeling dumber by the moment.
I actually used to like math.


two days ago my CYA was at 0
and my chlorine level was at 0
we added 'stabilized chlorine' that we had, until I could get a handle on how to read and understand this stuff.
Boyfriend says the chlorine was at 4 yesterday when he tested.
Thank you very much

 

[Richard320]

With CYA at 30, normal minimum FC is 4. You should try to never let it drop below that. But you will lose some chlorine to sunlight every day, so you target 6 so that it doesn't drop below 4 before you test and add again. If you get careless and do develop algae, you will need to raise the FC level to shock level to kill it off faster than it can reproduce. Shock level for 30 CYA is 12 FC. Unless you get algae, you may never ever need to go that high.

Whatever your CYA level is as it's rising, when you add more chlorine, aim for the target

 

[pooldv]

Welcome to TFP!

Just to make it official, 0 FC is not enough! If your FC is at 0 run for the bleach bottle, stop by Poolmath and add some pronto.

Richard is looking at the wrong line on the CYA chart. :-D

CYA of 30 has a minimum of 2, a target of 4 and shock of 12. So, never ever let it drop below 2. Target keeping it at 4, I would go 5 because I hate algae. And if you need to SLAM your pool the shock level will be 12. Clear? Like a pool?

It is safe to swim in your pool when:
Chlorine level is above the minimum and below shock level for your CYA
PH is between 7.2 and 7.8
Water is clear

Here is some Pool School for you to read.
Pool School - ABCs of Pool Water Chemistry
Pool School - Recommended Levels
Pool School - Recommended Pool Chemicals