Is this accurate?

[Philo]

Is this statement accurate?
" It will take much longer for FC levels to return to normal (swim ability) if you SHOCK with liquid chlorine vs. powdered Cal-Hypo ".

 

[tim5055]

Welcome to TFP!

If the amount of FC being added is the same with both products then the loss should be the same in either case? It sounds to me like the pool store is pushing CalHypo for the end of the year......

But, why are you "shocking"? Regular shocking of the pool is never necessary when you maintain the proper chlorine to stabilizer ratio.

I invite you to check out Pool School (link at the top of every page) to learn more about our methods of pool care.

Start with - Pool School - ABCs of Pool Water Chemistry

 

[woodyp]

The same amount of chlorine is the same amount of chlorine---should burn off, get used up at the same rate.

 

[Philo]

Doesn't the CC eventually increase over time and necessitate a SHOCK?

 

[woodyp]

SOMETHING had to happen for CC to increase. It doesn't just normally do so.


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[Philo]

What are examples of "SOMETHING had to happen"?

 

[woodyp]

Heavy bather loads and....."waste".

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[pabeader]

Large change in bather load, organic "stuff" being introduced into pool, algae bloom. Are just a few common things. Chlorine and sunlight take care of CCs all on their own.

Also, as long as your FC level is below the SLAM value for your CYA. And the other parameters are in line, it is safe to swim. So that could mean an FC of 10 is fine if your CYA is 50.

That's why it's so important to test for yourself and know what your CYA and other values are.

 

[tim5055]

Doesn't the CC eventually increase over time and necessitate a SHOCK?

Oops, Woody beat me to it.

Pool stores push regular shocking (weekly usually) due to the fact that their recommendations for FC are usually too low for the amount of stabilizer building up in the water. They say keep FC between 1-3 or 2-4 without taking into account the CYA.

I have never shocked my pool.

 

[Philo]

My CYA is at 35. What advantages would I have if I raised it to 60?

 

[pabeader]

Really, it's a wash. Less loss to sunlight, but a need for higher FC to insure proper sanitation and algae control.

BTW The scale for CYA is not linear so we just report it at the next higher number.

 

[tim5055]

My CYA is at 35. What advantages would I have if I raised it to 60?

Better "protection" from loss due to the UV rays of the sun. But, in a non-SWCG pool we would not recommend immediately taking it to 60. Probably take it to 50 and see how your daily chlorine demand is before taking it up to 60. 60 is the top end of our recommendations for a non SWCG pool and is generally only needed in hot sunny locations with immense sun on the pool all day long.


But, all of that is predicated on accurate testing. Pool stores are notorious for poor testing and the CYA test is the one they get wrong the most. Before adding CYA you need you r own test kit and get the number yourself.

 

[BuckeyeChris]

just to summarize for the OP:

1. stop trusting the pool store
2. Accurately determine your stabilizer level (cyanuric acid, or CYA) by investing in a recommended testing kit
3. Use the CYA/FC chart linked above to understand what your target FC level should be. If you stay above the minimum, your pool will stay sanitized and will also prevent algae growth.
4. A cya of 35 or 50 or 60 doesn't change the process. Since 99% of chlorine is bound to the stabilizer, the higher FC levels don't equate to higher active chlorine levels. Just keep above the minimum at all times for whatever your CYA is. There is some small decrease in burn-off for higher CYA levels, but at 30ppm you're already like 95% of the way there.
5. If you do have an algae bloom, we here don't SHOCK the pool. We raise the FC to a shock level and keep it above that level until 3 criteria are passed that let you know you've beaten the bloom.

You can swim when the FC drops below the SLAM, but at that point you are no longer outpacing algae growth and you could extend the process by a few days because of that small window where you let the FC drop. So, you'll have to decide how bad you want to swim.

You can keep the pool sanitized with low levels of active chlorine, but preventing algae growth requires a higher concentration. Weekly shocking, algaecides, phosphate removers, all those can prevent algae growth. But the TFPC method just requires add in some liquid chlorine every day to stay above that minimum. Then you never even need the other stuff. It's easier and cheaper.

CC are the result of the chlorine acting on organics in the water. For a healthy pool, this level is 0.2 or below. The UV from the sun destroys the CC. If your CC is higher than that, then your chlorine is working on a nascent growth: an algae bloom, or maybe a bunch of kids peed in the pool

Or maybe you're all set and was just wondering about Cal-hypo....

 

[Philo]

Thanks for all your help!