Saturday, November 04, 2006
Funny, huh? You know, Caveat Emptor, Let The Buyer Beware... I know. Never explain jokes. But doesn’t it just conjure up images of a big box store, replete with lights and calliope music and chock full of dubious gadgets and services being hocked by those same carny barkers that run the midway at the state fair?
I can see it now. There’s the Gypsy greeter who meets you at the door with a smile and a wave and then tries to pick your pocket when you walk by. Next up is his wife, Desdemona; Pet Psychic. There’s a booth that sells waterless cookware for drought stricken countries. Another guy sells flood insurance that doesn’t cover wind driven water or storm insurance that doesn’t cover floods, choose one and only one please. Then there’s the guy in the gray flannel suit selling shares of Enron stock. "Ten shares for a penny!" he cries. "You never know when it might come roaring back!"
You can drop your children off at Caveat Emptorium’s Free Day Care, where they can bob for apples in the piranha tank, play Russian Roulette with a single shot pistol, or sign up for swimming lessons at the shark tank.
And, yes folks, you guessed it, no need to worry about the kiddies having those red, runny eyes after cheating death and learning the backstroke because... wait for it... we’re using salt water.
I thought this week we ought to try to look on the bright side of salt systems. Let’s start with the manufacturer’s claims.
"Enjoy sparkling clean water, naturally and automatically. Never buy, mix or measure chlorine again. No more red eyes or itchy skin. No chemical smell. Just pure, clear water for day after day of fun in the sun."
That’s a quote off a marketing brochure. Let’s talk about that statement.
The Way Salt Works:
I bought this book a while ago, called Pool Chlorination Facts, by Robert W. Lowery. I love this book. If you don’t have it, and you have anything to do with taking care of the water quality of pools, you ought to get it. He’s a really smart guy who writes like a regular person. You may have already read his stuff without knowing it. If you ever took the IPSSA water chemistry exam and read those three handbooks they give out to prep for it, then you’ve read his work.
He talks about three types of chlorine generators; the brine system - or the portable bomb as I like to call it, the in-line system, and the in-pool system. Most everything we see in the field these days is the in-line system.
What I got from reading his description of in-line systems is that as the salty water passes through the cell, DC current is applied to it, and that causes three things to be formed; chlorine gas, caustic soda and hydrogen gas.
Now, if you look up the manufacturers sales pitch stuff, this is where they get that myth that the type of chlorine they generate is pH neutral because these three thing balance each other out. Not true. Much of the hydrogen gas rises to the surface and leaves the water. It gasses off, being a gas and all. Duh. That reduces the amount of hydrochloric acid created, and so the caustic soda - sodium hydroxide - neutralizes the hydrochloric acid and what’s left raises the overall pH.
But if you’re a pool cleaner like me, you already knew that without all them fancy words. Because every week when you go to your salt pools, the pH is through the roof. You ask the reps why and they shrug their shoulders and tell you that your meds must need tweaking because "our system only produces pH neutral chlorine. It has be something you’re doing wrong because we’re your friends and we would never lie to you."
So, you add gallons and gallons of acid trying to neutralize this skyrocketing pH, which if you read your handbook, Guide to pH, Alkalinity, Water Testing & Water Balance, you know that all that acid is burning off your Total Alkalinity. So, then you start adding DE scoops of baking soda - oh, excuse me, let me put my sales and marketing hat on... ahem... I mean Total Alkalinity Control, $18.99 a twelve pound box - and you’re stuck in this vicious loop of trying to maintain the 80 to 120 ppm Total Alkalinity that our industry preaches to you. But the pH of the baking soda you’re adding is 8.3, or eight times more base than the proper pH of pool water. So, again, you’re raising the pH. So, you pour more acid...
Hmmm... What’s wrong with this picture?
If your calcium hardness is 300 ppm and your water temperature is 88 (pretty common in August around here) and you know your pH is going to be 8.0 before you get back next week, then use your watergram and tell me where your Total Alkalinity ought to be. It lines up at about 22 ppm. Now, you’re going to adjust the water to 7.5 while you’re there. So, what’s the Total Alkalinity supposed to be for 7.5? 70 ppm.
You need to add a few points to it because I don’t think they took 3,500 ppm TDS (salt plus everything else) into account when they built your watergram.
Same example except now it’s dead of winter and the water temp is 45. The watergram lines up at 50 ppm Total Alkalinity at 8.0 and 155 ppm at 7.5
Plug in your own calcium hardness and your own high and low water temps for your region and do the math.
But wait. This can’t be right. Go to the inside door of the salt system controller. Right there it says to keep Total Alkalinity between 80 and 120 ppm and the manufacturer’s rep already told you that they’re your friends and they would never lie to you. So, we’re back to adjusting your meds.
You see, in the textbook world of The Way Salt Works, pH isn’t increased when the chlorine is made, because the hydrogen gas didn’t gas off. So the manufacturers didn’t have to put any money toward research that would promulgate new and unique guidelines for salt pools. Because it wouldn’t have sounded nearly as good saying "Never buy, mix or measure chlorine again", if they’d had to tack on, "But, boy, are you ever gonna need a buttload of acid and baking soda and a way more sophisticated test kit than that measly little two-way tester you got away with when you were using tablets. Now you have to learn about calcium levels because if you don’t, that pH swing inherent in our system is going to rip right through that pretty plaster of yours. If we don’t scale it with high pH and high Total Alkalinity when you try to follow current water chemistry guidelines, then we’ll burn holes in it with low pH and low Total Alkalinity when you only do half the job and just adjust pH, because at the lower Total Alkalinities, there won’t be as much buffer and so when you do your acid demand test and read off the table how much acid to add, it’ll have a more drastic effect on the pH than you anticipated because the table was computed with industry standard 80 to 120 Total Alkalinity in mind ...".
Sorry. I got carried away. My point is that salt pools are a different animal than tablet pools. Standing there and saying that they’re not, when even the pool cleaners know that they are, just gives guys like me more ammunition to point out that the Emperor Has No Clothes and he’s a liar to boot.
So where else was this rambling screed going? Oh, yes. I was supposed to enumerate the good things about salt systems...
Oh, yeah! Here’s one.
You know how some of the manufacturers call the mode that forces the system to maximum output for 24 hours Super Chlorinate? Well, that’s a lie. But the good news is, it’s only half a lie. Or some part of a lie. How much of a lie depends on how much Combined Chlorine is in your pool and where the salt system output is when you turn on Super Chlorinate.
For example, if you’re running your system at 100% output and you flick on Super Chlorinate, the system will produce at 100%. Hmmm... That’s not going to work.
But, if you’re running your system at 20%, and with water temp and swimmer load and debris load and every other load, that 20% setting produces 2 ppm Free Available Chlorine for you, but your Total Chlorine is 2.5 ppm, which means that 0.5 is Combined Chlorine and you need 7 to 10 times the level of Combined Chlorine to get to Breakpoint and burn it out, then going to Super Chlorinate for 24 hours, in this example, will create 8 ppm more Free Available Chlorine. Somewhere around 5 ppm Free Available Chlorine, you’ll hit Breakpoint and burn out that 0.5 Combined Chlorine, leaving you with 5 ppm Free Available Chlorine. Maybe. As you can see, this is an exact science.
So, how do they get away with labeling the switch Super Chlorinate? Because it’s just an industry term. It has no definition beyond what the user gives it. It may mean something to you as a pool professional. But that doesn’t mean they can’t redefine it to mean "produce at 100% capacity for 24 hours".
That way, they can say, "Never buy, mix or measure chlorine again" Which is way easier than saying, "Never buy, mix or measure chlorine again... as long as you never have to run your salt system at a level that precludes achieving an output 7 to 10 times your level of Combined Chlorine".
And that is a look on the bright side of salt systems. Caveat Emptor.
Labels: Debunking Salt
As far as the science of what you are describing with water chemistry and how a salt chlorinator interacts with the pool water. I think you should explore another book on the subject of chlorination. “The Handbook of Chlorination and Alternative Disinfectants” by George Clifford White, proposes an alternative to what you are describing, with respect to PH rise in water being chlorinated by this method. In reality, 1 molecule of Hydrochloric acid, and 1 molecule of Hypochlorous acid are coming from the anode side of the plates. On the cathode side, Hydrogen and Hydroxide are being produced. Hypochlorous acid is a weak acid, Hydrochloric is a strong acid. Sodium hydroxide is a strong base. The resulting solution is SLIGHTLY basic. Slightly basic you could relate to the pool in terms of the normal range of PH. A pool is slightly basic if the PH is 7.7. A pool is considered neutral if the PH is 7.6. It is not like you’ve got a solution with a PH of 14 being fed to the pool.
I don’t have the problems you describe in my pools. Once the pool gets over the initial demand for acid from the plaster curing, etc., a couple pints a week, at most, does the trick with none of the enormous alkalinity fluctuations you are describing. Notice that if you were sanitizing a pool with liquid chlorine and tablets, you would probably end up using a couple pints of acid a week as well.
As far as your opinion about the Super chlorinate button, you well know that for the chlorinator to truly “Super chlorinate” the pool it would have to be able to measure total and free chlorine, know the volume of the pool, etc. I have read all of the literature from all of the big three and none of them claim they can do that.
Relax dude, it’s not a conspiracy, it’s just a pool!
When it comes to the Super Chlorinate issue, what I know is that the pool owners have an idea in their head about what Super Chlorinate means. It is an idea that our industry spent years and years creating to keep pool water safe and comfortable to swim in. And what I know is that the Salt Folks have cheapened that definition. Pool owners aren't supposed to know the nitty gritty details of Super Chlorinate. That's what they pay us to do for them; be their representative and protect them from companies that would sell them crap.
What I was describing with my scenario about the fluctuations in TA was what happens if you try to maintain the water chemistry guidelines promulgated by our industry. Trying to hold a 120 ppm TA, which is recommended by the salt system manufacturers, in a pool that is going to see a pH excursion from 7.5 to 8.0+ in a week - which I have to disagree with you about your "slightly basic" pH in salt pools - is a hard thing to do. You have to add tons of acid to bring down that higher TA and start to have an effect on the pH.
My point was, and is, and it goes back to properly laying the groundwork before product launch, that new water chemistry guidelines should have been laid out for salt pools when the systems were introduced. There are guys out there who just follow the guidelines; 80 to 120 TA and 7.5 pH. You can blame them for not knowing as much as you do, but that just plays right back into the reps hands by dismissing genuine issues about poor product introduction and training.
And at the end of the day, there are still environmental issues to contend with. It is easy to be distracting by attacking one or two points in the body of work that I'm presenting here. Try to find a way to tell me how good salt is for the soil, and for plants, and for waste water treatment. Every problem starts small, like slightly elevated salt levels at the waste treatment plant, and end up a big consumer price tag once every pool is salt and every home has a water softener.
I hope you'll continue to contribute. I don't think we are that far apart, really. I especially felt that when I read, "granted, some of the reps in our industry have less than 100% integrity".
And, if the unit doesn't truly superchlorinate (and that's not a lie) why is it on there?
Also a pool guy said "You have to go to one of the technical reps to get the more detailed aspects of how the big three’s products work."
I think you are giving some of these people too much credit. There are a number of these "technical" people making erroneous statements because they heard something from someone. Then they give a presentation in front of a group and repeat what they heard as though it was their own verified experience or fact. Then the people that went there to learn go away a dissiminate this garbage to everyone they meet. So another great myth is born.
That's just my experience... not some BS someone told me.
Oh and yeah.. one other question. Do you really test for free and total chlorine?