Jandy SWCG's "optimal" water conditions: why raise CYA?

[famousdavis]

Waterbear,

I tested with the K-2006 kit this morning. TA is 90, pH 7.4, CH 280, FC 7.0 (the pool's still coming off Sunday's shocking), CC 0.5 (I didn't re-test CYA because it uses so much reagent).

This weekend, when I have the pros re-test the water, I'll test my CYA and do what's necessary to boost up the CYA so I can keep the FC around 4 PPM.

I got the idea that you shock a pool on a regular basis because the Pinch-a-Penny test results print-out says that that's one of the ABC's for a healthy pool -- you shock it once a week. I'm intrigued that you and others don't do this, yet don't have troubles with your pool. I thought that over time the combined chlorine becomes a problem, so shocking weekly pretty much elminates any CC you have in the water? If you only shock when the CC reaches some threshold, what is that threshold?

[waterbear]

I got the idea that you shock a pool on a regular basis because the Pinch-a-Penny test results print-out says that that's one of the ABC's for a healthy pool -- you shock it once a week.
Yep, and they can sell shock that way on a regular basis. Works better for those that don't have salt pools but you get the idea. Pool stores are in the business of selling chems and things like shocking weekly and pushing phosphate removes (and selling "mineral systems") hellp increase their bottom line. Shocking once a week is really one of the ABCs of a healthy pool STORE since it increases their sales.

I'm intrigued that you and others don't do this, yet don't have troubles with your pool. I thought that over time the combined chlorine becomes a problem, so shocking weekly pretty much elminates any CC you have in the water? If you only shock when the CC reaches some threshold, what is that threshold?

If you have CC over .5 ppm then shock. If you keep the FC in line with the CYA level by keeping it at 5% of the CYA in a salt pool or following the Best Guess Chart (that I linked to above) then the fact of the matter is that you will basically not have CC. If you try and run your FC lower than this you will and will need to shock. Period. The correct FC for the CYA will keep einough 'active' chlorine in the water. Also, in a salt pool the water in the cell is being 'supershocked' to very high chlorine levels when the cell is on.

Trivia: for most people the 'threshold' where their nose can detect CC is .4 ppm.

[famousdavis]

Ahhhh, this site is so informative! What you're saying makes sense -- very good sense. I'm liking more and more the idea of keeping the pool at 4 PPM FC / 80 PPM CYA and do periodic testing for CC, shocking whenever it's necessary. If that happens just once a month, I'll likely opt to buy liquid chlorine and shock that way rather than use the Boost button on the salt cell. Not too much trouble, and the quickness of the liquid chlorine may be more effective than the 24-hour boost cycle. Avoiding weekly shocks saves $$$ and, with the right water chemistry, doesn't create a greater risk of algae, either. Very nice.

Our pool is getting a LOT of use this summer because 1) it's new, 2) there's 6 of us living in my home, 3) all 6 like to invite their friends over to swim. So I won't be surprised if I have to shock the pool somewhat frequently, but perhaps I don't need to do it weekly afterall, Pinch-a-Penny's advice be danged.

For the next few days, I'll leave the SWCG set at 50% for the pump's regular 8-hour cycle (I run the pump after the 8 hours if people are in the pool, but I don't switch on the SWCG). I want to see how quickly the FC is depleted with this setting. Once it reaches 4 PPM, I'll bump up the SWCG to 60% or 70% to try and get a net-zero change to the FC. I do have a variable-speed pump, so I certainly could run the pump longer and a lower speed if I need to.

It's been fun trying to figure out all this stuff. This forum has been a terrific source of knowledge, real-world experience and expert advice. I already know more about pool chemistry that several pool-owning friends who have owned pools for years and years!

[Watermom]

It's been fun trying to figure out all this stuff. This forum has been a terrific source of knowledge, real-world experience and expert advice. I already know more about pool chemistry that several pool-owning friends who have owned pools for years and years!

Because of what you've learned on the forum, you probably already know more about pool chemistry than the so called 'pros' who are testing your water for you at the pool store!

[famousdavis]

I think you're right! I certainly trust my own shaky judgment more now than the guy over at The Pool Store that uses a test strip to test my water. He's the fellow that sold me a $25 bottle of phosophates remover, causing my sparkly pool to turn cloudy, then gumming up my nearly-clean DE filter to the point I had to backwash it. I won't add that stuff in again! Wish I had read more deeply in this forum before I blindly followed his advice.

I don't over-estimate my knowledge -- I'm a pool chemistry neophyte still -- but I've got a reasonable handle on pool chemistry now, and a majority of what I've learned has come from this website and the little pamphlet that Taylor helpfully includes inside their K-2006 kit. I've hit a few other pool-related websites for information, too, but this site and the people in it have been by far the most helpful. The fact you have such active and knowledgeable moderators makes a huge difference. What I'm most pleased with is I've got a strategy for how I want to handle my pool maintenance duties that I've quickly developed, without having to go through a terribly long process of trial-and-error. I'm feeling pretty confident about keeping my pool clear and clean (and if I DO run into trouble, I'll come back to this forum to find some answers).

[Watermom]

I've hit a few other pool-related websites for information, too, but this site and the people in it have been by far the most helpful. The fact you have such active and knowledgeable moderators makes a huge difference.

Thank you!

[rpoldervaart]

and do periodic testing for CC, shocking whenever it's necessary. If that happens just once a month, I'll likely opt to buy liquid chlorine and shock that way rather than use the Boost button on the salt cell. Not too much trouble, and the quickness of the liquid chlorine may be more effective than the 24-hour boost cycle. Avoiding weekly shocks saves $$$ and, with the right water chemistry, doesn't create a greater risk of algae, either. Very nice.

You're starting to believe, but I don't think you're quite there yet. When Waterbear says you don't have to shock, you really don't have to shock; not even monthly. If you keep the FC and other chemicals where they should be, you shouldn't ever have to shock, unless something else happens.

I live in Houston with a SWCG and only throw in some bleach after a big pool party with my kid's friends, or when a hurricane brings through a bunch of dirty rain. If I got lazy and didn't check my pool for a while and saw the chlorine got low, I might through in a little bleach to bring it back up. I very rarely ever get any CC.

So if you keep a nice balanced pool, you won't have to "periodically" shock your pool.

Robert

[waterbear]

You're starting to believe, but I don't think you're quite there yet. When Waterbear says you don't have to shock, you really don't have to shock; not even monthly. If you keep the FC and other chemicals where they should be, you shouldn't ever have to shock, unless something else happens.

As it says in my sig "You can lead a pool owner to water, etc. etc. etc."

Don't worry, We've put the pod under his bed and when he awakes he will be one of us!
(apologies to Keven McCarthy/Donald Southerland)