Closing AGP - what is shock level?

[afreil]

We are preparing to close our saltwater AGP for the first time. I have read the instructions in pool school and various other pool articles. All of them say to bring the pool water to "shock" level. However, none of them explain what the heck "shock level" is. Currently our FC is about double what it normally was during the summer. Here are my latest test readings:
FC: 9
Ph: 7.6
TA: 80
CYA: 45

Am I good to close with these readings?

 

[woodyp]

Please refer to the Chlorine/CYa chart in Pool School.

 

[jblizzle]

We now call is SLAM level, but as woody said, you can find the chart in Pool School here: pool-school/chlorine_cya_chart_shock

It is a function of your CYA level and for you it would be around 18ppm.

 

[afreil]

So, if I'm understanding this correctly, I need to dump approximately 3 gallons of chlorine into my saltwater pool prior to lowering the water level and closing?

 

[jblizzle]

Sounds reasonable, although I did not check the dose with PoolMath.

 

[jblizzle]

Estimating you volume at 18k, to raise the FC from 9ppm to 18ppm would require two 121oz bottles of 8.25% bleach or 2.75 gallons of 6%.