shocking pool

[bribri]

I'm curious to know if the shocking process with a cya of 70 uses the same amount of chlorine a pool with cya of say 30? I know the ppm will be higher but would there be a difference in the total amount used?

 

[duraleigh]

It doesn't make a huge difference.

Although, it is VERY difficult for folks to wrap around bringing their FC to almost 30ppm and then holding it there when CYA is 70.

We suggest an ideal shock value of 20-30 CYA so your shock FC now is about 12 and that is much more palatable to many.

 

[woodyp]

Makes sense that to get more ppm of FC in the water you'd have to add a larger total amount of it.

 

[elwood58]

Pool Calculator is your friend.

 

[bribri]

yes. I understand that you have to bring the ppm to 30, but will the total chlorine usage from start of shock to 2 week after overnight loss test (pass) be the same, regardless of the cya in the pool. I'm trying to get my head around the high shock level. Oh yah I have a swg. I would think it would have to be the same because there is only so much organics in the water.

 

[linen]

You will lose a little more FC from the sun during the day at the required higher FC levels even with the higher cya.

 

[jcowart]

I know I helped a friend last summer with her pool. I can say even with high CYA the loss was higher at shock level even with the CC coming down. Once the process was over it leveled out. I just figured the FC overcame the CYA and a lot was lost to the sun. Once it was back down in the range pool calc called for her loss per day averaged 1.5ppm. Side note is she is no longer pool stored and took control of her pool.

 

[chem geek]

You are correct that the rate of FC loss, even in percentage terms, is higher at higher FC/CYA ratios such as shock level. And yes, this is because a higher percentage of the chlorine is unbound from CYA and therefore breaking down from the UV in sunlight more rapidly.