How much 10% liquid chlorine to shock my pool

[Mathwiz]

Hi, I have a 18X36 vinyl liner pool that I calculate to have 26k gal. I opened the pool and started treating the water. Here are my results from this AM.

FC=1.0
CC=6.5
pH=7.45
Alk=120
CYA=35
I know all numbers are good except combined chlorine. I have been putting in 2 bags per day of Sodium Dichloro (55% available chlorine) for 4 days now and the CC just continues to creep up. Apparently, the 2 bags is not really shocking the pool. The water is crystal clear and I want to put the brakes on the CYA so I bought 6 gallons of 10% bleach.

My question is how much 10% bleach do I need to put in to shock the pool? My fear is bleaching my liner which is only 1 year old.

Thanks for any help.
Mike

 

[mknauss]

Welcome to the forum!
Follow the SLAM Process. Your CYA is recorded as 40 ppm as you round up. The SLAM level FC is 16 ppm. Raise it to that and Maintain it until you pass the three criteria.
I suggest you read ABC's of Pool Water Chemistry.

 

[Mathwiz]

Thank you for the welcome. So do you think 2 gallons will get me to 16ppm? I once knew of a calculator to give me the amount, but I can't find it.

 

[mknauss]

Use Poolmath.
One gallon of 10% liquid chlorine added to 10000 gallons of water will raise the FC by 10 ppm.

In your pool, 4.5 gallons of 10% will raise the FC by 16ppm. This is NOT one and done, you must test your FC and raise it back to 16 ppm every few hours.

 

[Mathwiz]

Thanks, I will check out Poolmath.

 

[mguzzy]

Wow.. is this a record for the amount of time passed between joining and posting? a Belated Welcome!

If you have a CC of 6.5 you have a bloom bubbling in the pool. Just because its clear doesn't mean there is no algae. And the fact that you keep adding dichlor with no apparent effect tells us the algae is consuming it as fast as you are putting it in. So follow Marty's sage advice and perform a SLAM before it gets worse.

 

[Mathwiz]

Probably is. Thanks for the welcome. I usually just read a lot to figure out what I need, however this time I was a little puzzled. I appreciate your input. I just added the prescribed amount of 10% liquid. I will retest in a few hours and stay with the regimen. This site is really a plethora of intelligent information with people like you and mknauss on here. With the current situation concerning chlorine availability, even more so. Thanks
again for the quick help.

Evidence that looks can be deceiving.

 

[IceShadow]

Has any non-chlorine shock been added that might be reading as CC?

 

[Mathwiz]

Has any non-chlorine shock been added that might be reading as CC?

Until today I have been using one lb bags of di-chlor granular chlorine with 58% available chlorine mainly to get some stabilizer in the pool, so I guess the answer to your question would be "no". I have used non-chlorine shock in the past, but not since I opened the pool this season. Thanks for bringing up a valid point. I am happy to report that after adding 4.5 gallons of 10% bleach throughout the day, my CC has dropped from 6.5ppm to 2.5ppm. I will check again just before sunset and probably add another 1/2 gallon before calling it a day and rechecking in the morning. I anticipate good results.