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

[famousdavis]

(BTW, I just subscribed to this forum thanks to your helpfulness).

I've found that whenever the pH goes to 7.2, it rises to 7.4 within the same day. So, although the pH probably was 7.2 after I added acid, it'll be 7.4 by the time I get home tonight. But I'm getting your point that shades of adjustment are better than leaps in pH adjustment; I'll re-calcualte going forward on what it takes to bring the pH down from 7.8 to 7.4, rather than 7.2.

I added the baking soda because my "optimal" range (noted by Jandy, above) is 80 - 120 PPM for TA, and since I was on the lower end of optimum, I opted to optimze my TA by bumping it an optimal middle of 100 PPM. ;-)

FC was admittedly low @ 1.5 PPM. Over the last few days of last week, I was just watching to see how my FC would fall when I ran the SWCG @ 50% for 8 hours a day. That seemed to cause it to have a net loss of about 1 PPM per day (it was 3.5 on Friday morning, 2.5 on Saturday morning, 1.5 on Sunday morning), so I know now that I'll need to bump up the salt production higher than 50%. Also, I wanted to see what my OTO kit would read, knowing it's not as accurate as the K-2006. The OTO kit is reasonably accurate (OTO showed 1.0 when my K-2006 showed 1.5; OTO showed 2.0 when my K-2006 showed 2.5; OTO showed 2.0 when my K-2006 showed 3.5). The OTO kit, however, doesn't do a good job at all at reading high levels of chlorine. As I mentioned, the K-2006 showed 12.5 FC this morning, but my OTO's yellow color this morning matched the 3.0 -- it didn't even have a bright orange color that would match the 5.0 color scale). So, it seems the OTO is good for letting me know that I have chlorine in the pool, but not so good at letting me know the upper ranges of how much chlorine. (Note: I have my elementary-aged kids do the OTO test daily).

So, in sum, it seems good to target a higher FC reading of not less than 3 PPM. Since Jandy recommends against > 4.0 PPM, while other sources say an upper range of 4 PPM is within the ideal range, I'll shoot for FC of 3 to 4 PPM. I could boost my CYA up to 80 and if I kept the FC at 4 PPM, I'd still be within the 5% of CYA.

As for shocking, I'll have to mull over that a bit to figure out what I'm willing to do. I guess weekly shocking isn't as important to do if the CC doesn't warrant it. If I just use a bleach shock maybe once a month during these warm months, maybe that's a better way to go. And I suppose I could always still hit the Boost button if I wanted, if I noticed anything less than the sparkle that I have always had in the pool so far. BTW, in a 16,000 gallon pool, how much bleach would I need? I just Googled and found a calculator that says that if my pool is 3 PPM and I want to raise it to 20 PPM, I'd need 4.5 gallons of bleach! Does that sound right? How long would we have to wait before re-entering the pool following such a shock?

One last question. I get that pool store chlorine is the same as grocery store bleach, just in a stronger concentration. Is the choice of which to use simply a financial one -- which is less costly, given how much of each liquid I'd have to add to the pool? It seems like the risk of a leaking liquid chlorine jug is greater since they're re-used over and over, and the higher concentration is more toxic, whereas the grocery store bleach is brought home, used once, then pitched into the recycle bin. It's easier for me to go to the grocery store, too, as they open early and stay open late, 7 days a week.

Thanks for your guidance, Waterbear. You've earned the site's $14 subscription fee. :-)

[waterbear]

I added the baking soda because my "optimal" range (noted by Jandy, above) is 80 - 120 PPM for TA, and since I was on the lower end of optimum, I opted to optimze my TA by bumping it an optimal middle of 100 PPM. ;-)
Except that optimal for a salt pool (or any pool using unstabilized chlorine for that matter) would be the BOTTOM of the range. Drop it back to 80 ppm.

FC was admittedly low @ 1.5 PPM. Over the last few days of last week, I was just watching to see how my FC would fall when I ran the SWCG @ 50% for 8 hours a day. That seemed to cause it to have a net loss of about 1 PPM per day (it was 3.5 on Friday morning, 2.5 on Saturday morning, 1.5 on Sunday morning), so I know now that I'll need to bump up the salt production higher than 50%. Also, I wanted to see what my OTO kit would read, knowing it's not as accurate as the K-2006. The OTO kit is reasonably accurate (OTO showed 1.0 when my K-2006 showed 1.5; OTO showed 2.0 when my K-2006 showed 2.5; OTO showed 2.0 when my K-2006 showed 3.5). The OTO kit, however, doesn't do a good job at all at reading high levels of chlorine. As I mentioned, the K-2006 showed 12.5 FC this morning, but my OTO's yellow color this morning matched the 3.0 -- it didn't even have a bright orange color that would match the 5.0 color scale). So, it seems the OTO is good for letting me know that I have chlorine in the pool, but not so good at letting me know the upper ranges of how much chlorine. (Note: I have my elementary-aged kids do the OTO test daily).

So, in sum, it seems good to target a higher FC reading of not less than 3 PPM. Since Jandy recommends against > 4.0 PPM, while other sources say an upper range of 4 PPM is within the ideal range, I'll shoot for FC of 3 to 4 PPM. I could boost my CYA up to 80 and if I kept the FC at 4 PPM, I'd still be within the 5% of CYA.
Bring the CYA up to 80 ppm and you will be able to keep the 4 ppm FC without a problem and will be able to lower your cell output. I am concerned that your unit might not be sized for your pool if running 8 hours a day at 50% is only bringing the FC to 1.5 ppm. Hopefully you have a 2 speed or multi speed pump so you can run the pump for a longer run time if needed to maintain the FC where needed. Jandy's recommendatons are based on some outdated data. If you have not done so please read the 'Best Guess Chlorine Chart' for some background.

As for shocking, I'll have to mull over that a bit to figure out what I'm willing to do.
Easy answer, your don't have to do anything! Get the CYA to 80 ppm and the FC to 4 ppm and you will not need to shock. I don't know where you go the idea that you have to shock a pool on any regular basis. Last time I shocked my pool was after returning from a 2 week vacation last July and my pool was shut off while I was gone. Because of the borates in my water my pool was only slightly cloudy and a shock to 20 ppm FC took care of it and I was swimming a day later! Normally I never shock and you should not need to either!


One last question. I get that pool store chlorine is the same as grocery store bleach, just in a stronger concentration. Is the choice of which to use simply a financial one -- which is less costly, given how much of each liquid I'd have to add to the pool? It seems like the risk of a leaking liquid chlorine jug is greater since they're re-used over and over, and the higher concentration is more toxic, whereas the grocery store bleach is brought home, used once, then pitched into the recycle bin. It's easier for me to go to the grocery store, too, as they open early and stay open late, 7 days a week.
Generally pool store chlorine is less expensive here in Florida than bleach is. The carboys usually do not leak. (I have filled enough of them up myself when I worked in the biz. NOT a fun job in the hot summer sun!) The one point to remember is that the stronger the bleach the faster it loses strength. 12.5% really is not any more 'dangerous' than 6%. You need to treat all pool and household chemicals with respect. However, we tend to think of our common household products like bleach and baking soda as 'safe' because they are familiar.
For example, did you know that baking soda is actually more toxic than cyanuric acid (CYA)?
Thanks for your guidance, Waterbear. You've earned the site's $14 subscription fee. :-)

Ironic thing is that I am a moderator on a completely different pool and spa forum! I hope Ben appreciates it!

[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).

[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)

[BigTallGuy]

I just posted this in another thread about an hour ago. Please read.

Absolutely, You need Stabilizer. Here is a bit of a testimonial. Being a real card carrying "Big Tall Dumb Guy" with a SWCG, my scatter brain told me I didn't really care too much about the CYA (stabilizer) levels. So when I replaced my pool liner last year and installed a SWCG, I added some CYA but not enough. My Chlorine levels were good with my CYA at 25 - 30 PPM, AND ALL SEEMED GOOD.

After all, my chlorine is FREE, Right? Wrong! Chlorine isn't "free" when you have to run your pump twice as long to keep the Chlorine levels up (NOT TO MENTION BURNING OUT YOUR CELL).

I had to run my system for 7 hours a day to keep from running out of chlorine at sunset. I decided to stop being so stupid and I raised my CYA to 45 ppm and I am now running my pump for 4 hours a day. The $10.00 bottle of stabilizer will save me hundreds (Plural) yes hundreds of dollars in electricity.

You can learn a lot from a BIGTALLDUMBGUY!