Why do the AFO text, the PPOA.org articles and the content of the PumpRoom Press always show quotation marks around the word free in the silly phrase “free” chlorine? ‘Cause it’s never all free to work for us, that’s why.
You know that some percentage of near-useless OCl – (that hypochlorite ion) always exists along with the HOCl – the real thing – the associated hypochlorous acid that does the all-important oxidation and sanitation for us. The ratio of HOCl to OCl- (missing that critical H+) varies rapidly according to changes in the water’s pH.
This “disassociation” business changes extremely as pH moves around. The super-weak hypochlorite ion (OCl-) exists at about 25% of the free/available chlorine when the test-kit reading is at pH 7 while, at pH values approaching 8, the weak sister is dominant at roughly 75%. So FAC isn’t, ever, all “FAC” – it’s never all available.
Whoever invented the FAC term knew more chemistry than he did the English language. While “free” in the term being discussed here means not combined (not ammonia products – remember smelly chloramine?), “available” remains pretty silly as the pH approaches 8.0, and not so hot even at typical pH values near 7.4.
An even more absurd term is CAC, combined available chlorine. Virtually NONE of that chlorine compound is “available”. In Dr. White’s famous Handbook of Chlorination, he states: “The term ‘available chlorine’ has no place in the field of water and waste treatment...” He goes on to describe the archaic origins of the term.
So let’s quit using those silly terms FAC, TAC and CAC, and call ‘em what they are... “free”, “total” and “combined” chlorine.
Wednesday, February 18, 2009
Friday, June 20, 2008
Our wonderful CDC posts new fecal-response guidelines!
Give me a break! Are there no math graduates at the Centers for Disease Control? The absurdity of keeping a public pool closed at “20 ppm” for “12.75 hours”, between pH 7.3 and 7.5 and a temperature of “about 77 degrees”… in order to deactivate all those nasty, bad cryptosporidiosis pathogens in lane two before they swim to lane one or three is truly ABSURD! Yes, we need to create significant Oxidation Potential (ORP) in the water after a fecal accident and, yes, it needs to be kick-butt, but to define the deactivation time as 12.75 hours (heavens, not 12.5 or 13 hours!) is mathematically – effectively and statistically – ridiculous! We at PPOA ask forgiveness, as the CDC is trying hard to make things safer for those swimmers in our public pools; it is just the crazy nature of their false “precision” that troubles us!
Twenty parts per million of “chlorine” (do they mean associated HOCl?) can produce an Oxidation/Reduction Potential of near 850 mV – a truly effective, highly qualitative sanitation value. But so does 16 ppm – even 30 ppm – as the functional value of each, exact residual level declines greatly with the increasing total of readable quantities. Cyanuric acid, along with every tenth decade of pH – and certainly considering the presence of those annoying ammonia compounds of chlorine called chloramine – have huge influences on the work value of the sanitizer in the water. Test-kit readings are simply a working range, not a functioning value! A tenth of a pH decade or 10 ppm CYA can have far more influence on the work value of a free-chlorine residual than a few ppm up or down. (And what does “between pH 7.3 and 7.5” mean? Literally it’s 7.4, not sorta’ but exactly.)
We know that many of our “public” pools are not fitted with ORP controllers, those wonderful automation devices managing the chemical pumps while reading the actual work value… but we must be aware of the working ranges of those variables we can measure. Let’s look:
“20 ppm” is hugely variable in its work value in the presence of many other variables. It can represent the same ORP (oxidation/reduction potential, the quality of the process) as just 2 ppm at a low pH, no combined chlorine and no cyanuric acid, while comparing it to as much as 30 ppm with 50 ppm CYA, a bit higher pH (like 7.6) and a dominance of chloramine.
Finally, and only if we actually “do it right”, we are told we’ll be “inactivating” 99.9% of those nasty pathogen, meaning just 0.1% will be living and thriving, swimming a bit slower but continuously infecting about one out of a thousand of us… So count all those folks in your pool and, if you’re among about a hundred patrons out there swimming, you only have just one lousy chance in ten of getting that deadly cryptosporidiosis!
Those of us who have been swimming from high school (captain of the 1956 team) through college (captain of the 1960 team) and much more since don’t seem to be too concerned about fecal sanitation. Check PPOA articles in our Pumproom Press ~ issues 4, 6, Summer 98 and issue 36. From cheek wash to brown trout, pool stools and baby-Ruth floaters, you’ll understand that our ability to resist contamination in human infestation is pretty doggone’ wonderful. Otherwise, this contributor would surely be sick today, not interested in ever going swimming again nor in writing this piece!
Twenty parts per million of “chlorine” (do they mean associated HOCl?) can produce an Oxidation/Reduction Potential of near 850 mV – a truly effective, highly qualitative sanitation value. But so does 16 ppm – even 30 ppm – as the functional value of each, exact residual level declines greatly with the increasing total of readable quantities. Cyanuric acid, along with every tenth decade of pH – and certainly considering the presence of those annoying ammonia compounds of chlorine called chloramine – have huge influences on the work value of the sanitizer in the water. Test-kit readings are simply a working range, not a functioning value! A tenth of a pH decade or 10 ppm CYA can have far more influence on the work value of a free-chlorine residual than a few ppm up or down. (And what does “between pH 7.3 and 7.5” mean? Literally it’s 7.4, not sorta’ but exactly.)
We know that many of our “public” pools are not fitted with ORP controllers, those wonderful automation devices managing the chemical pumps while reading the actual work value… but we must be aware of the working ranges of those variables we can measure. Let’s look:
“20 ppm” is hugely variable in its work value in the presence of many other variables. It can represent the same ORP (oxidation/reduction potential, the quality of the process) as just 2 ppm at a low pH, no combined chlorine and no cyanuric acid, while comparing it to as much as 30 ppm with 50 ppm CYA, a bit higher pH (like 7.6) and a dominance of chloramine.
Finally, and only if we actually “do it right”, we are told we’ll be “inactivating” 99.9% of those nasty pathogen, meaning just 0.1% will be living and thriving, swimming a bit slower but continuously infecting about one out of a thousand of us… So count all those folks in your pool and, if you’re among about a hundred patrons out there swimming, you only have just one lousy chance in ten of getting that deadly cryptosporidiosis!
Those of us who have been swimming from high school (captain of the 1956 team) through college (captain of the 1960 team) and much more since don’t seem to be too concerned about fecal sanitation. Check PPOA articles in our Pumproom Press ~ issues 4, 6, Summer 98 and issue 36. From cheek wash to brown trout, pool stools and baby-Ruth floaters, you’ll understand that our ability to resist contamination in human infestation is pretty doggone’ wonderful. Otherwise, this contributor would surely be sick today, not interested in ever going swimming again nor in writing this piece!
Thursday, April 24, 2008
Pool covers save more energy than all other efforts put together!
Where do pool-blanket energy savings really come from? This question is the most significant yet least understood consideration when pool owners consider the use of pool-blanket systems. In the simplest terms, swimming pool blankets stop evaporation. It's only incidental that they insulate to a small degree. Insulation, the property usually attributed to blankets, contributes from one or two percent of the energy savings for pools (a little more when used on outdoor spas). Evaporation retardation is overwhelmingly the larger contributor, up to 50% savings on energy usage!
Without delving into the physics too deeply, a brief "scientific" explanation helps our pool operator to understand the significance of evaporation: Water, that master-standard chemical, requires just one “calorie” (an energy unit) per milliliter (cubic centimeter) to raise its temperature exactly one degree Centigrade. Conversely, it loses one calorie as the temperature drops one degree. However, vastly increased amounts of energy are either given off or required to be "taken in" for changes of state − that's the transition between the vapor, liquid and solid states of water. For the shift from liquid to vapor, the energy required is called the "heat of vaporization" − 540 calories. It takes five hundred forty times as much energy to vaporize any quantity of water than it does simply to raise that same quantity of water one degree Centigrade! That's a killer of a statement. Read it again...
Here is an example: We have an outdoor spa at a ski resort with snow on the ground. Water temperature is 42 degrees Centigrade (103 degrees F) and the air temperature is freezing − zero degrees C (32 degrees F).
The zero-Centigrade air that is in contact with the warm water, (42 degrees C,) naturally takes energy form the water. Ultimately, 42 calories are lost for each milliliter of water if it cools to the temperature of the air (or this much energy must be replaced by the heater to avoid that temperature drop). At the same time, each tiny milliliter of water that evaporates absorbs fully 540 calories from surrounding water... or twelve times the energy-replacement requirement as the conduction energy exchange. A spa cover was essential in this true-life example in order that the skiers could shush up and take a warm, relaxing soak.
Wind and humidity as well as radiant energy and ground conduction affect this ratio, but not enough to invalidate the example. The point is this: an impervious membrane stretched across the surface can halt evaporation entirely, thus saving a huge portion of heat energy which otherwise would be lost! And that membrane can be anything; it could even be Visqueen or Saran Wrap! Something more substantial, removable and reusable might be a better idea, of course.
Cover those pools! It’ll pay your salary!
Without delving into the physics too deeply, a brief "scientific" explanation helps our pool operator to understand the significance of evaporation: Water, that master-standard chemical, requires just one “calorie” (an energy unit) per milliliter (cubic centimeter) to raise its temperature exactly one degree Centigrade. Conversely, it loses one calorie as the temperature drops one degree. However, vastly increased amounts of energy are either given off or required to be "taken in" for changes of state − that's the transition between the vapor, liquid and solid states of water. For the shift from liquid to vapor, the energy required is called the "heat of vaporization" − 540 calories. It takes five hundred forty times as much energy to vaporize any quantity of water than it does simply to raise that same quantity of water one degree Centigrade! That's a killer of a statement. Read it again...
Here is an example: We have an outdoor spa at a ski resort with snow on the ground. Water temperature is 42 degrees Centigrade (103 degrees F) and the air temperature is freezing − zero degrees C (32 degrees F).
The zero-Centigrade air that is in contact with the warm water, (42 degrees C,) naturally takes energy form the water. Ultimately, 42 calories are lost for each milliliter of water if it cools to the temperature of the air (or this much energy must be replaced by the heater to avoid that temperature drop). At the same time, each tiny milliliter of water that evaporates absorbs fully 540 calories from surrounding water... or twelve times the energy-replacement requirement as the conduction energy exchange. A spa cover was essential in this true-life example in order that the skiers could shush up and take a warm, relaxing soak.
Wind and humidity as well as radiant energy and ground conduction affect this ratio, but not enough to invalidate the example. The point is this: an impervious membrane stretched across the surface can halt evaporation entirely, thus saving a huge portion of heat energy which otherwise would be lost! And that membrane can be anything; it could even be Visqueen or Saran Wrap! Something more substantial, removable and reusable might be a better idea, of course.
Cover those pools! It’ll pay your salary!
Monday, March 31, 2008
Solving Cloudy Water Mysteries
Here’s a water condition that neither the amateur nor the expert can figure out. Can’t, that is, until she or he knows a lot more about the pool and its environment than does any swimming-pool wizard who might walk up to your pool simply to observe the water...
Cloudy water, no doubt, is the nemesis of many a pool operator. It so often seems to have an un-detectable and mysterious source. ‘Truth is, there're probably a dozen sources – at least four of which are quite common, and the resulting water looks the same, lousy.
Here’s a list of my favorite reasons for pool-water turbidity, and some of what to do about them. Could any of these be the cause for your cloudy water: organics, failing paint, precipitation, diatomaceous earth, failing plaster, entrained air, other suspension, and sabotage. That motel pool with crystal clear water all week may, for any of these reasons, cloud up substantially over the busy football weekend, not to clear again 'till Tuesday.
Maybe the most common cause for turbidity is just plain dirty water. That’s organic material you’re looking at, or it’s the products of the incomplete oxidation of suspended organics, and it means you’re not oxidizing near’ well enough in your high-load pool.
Notwithstanding such causes as the nearby rice-field burning or the neighboring dusty, windy construction site, poor oxidation in any pool water will eventually allow cloudiness to develop. Remember that the filter's job is to handle the big particulate and the non-oxidizables; your chemical oxidizer has the far greater job in producing polished water than the mechanical straining performed by the filter.
The chlorine product (or other “oxidizer”) must handle the organic solids introduced into, and suspended in, your pool. If your ORP is impaired in any way, by high pH, dominance of chloramines or excessive stabilizer, the oxidation process may be slowed by an order of magnitude (1/10th!) or more. Cyanuric acid alone, for example, can reduce the equivalent ORP of 1 ppm “free” chlorine to that of an un-stabilized .2 ppm. And that’s at only 20 ppm CYA! More stabilizer? Enjoy your cloudy pool.
So I hope your pool is automated by a device that measures and controls the oxidation potential of whatever sanitizer you’re feeding. Setting a value of 780 to 800 mV will cause a feed of, well, whatever it takes to oxidize those suspended organics and clear up that pool. And go easy, please, on that Cyanuric Acid stabilizer!
Cloudy water, no doubt, is the nemesis of many a pool operator. It so often seems to have an un-detectable and mysterious source. ‘Truth is, there're probably a dozen sources – at least four of which are quite common, and the resulting water looks the same, lousy.
Here’s a list of my favorite reasons for pool-water turbidity, and some of what to do about them. Could any of these be the cause for your cloudy water: organics, failing paint, precipitation, diatomaceous earth, failing plaster, entrained air, other suspension, and sabotage. That motel pool with crystal clear water all week may, for any of these reasons, cloud up substantially over the busy football weekend, not to clear again 'till Tuesday.
Maybe the most common cause for turbidity is just plain dirty water. That’s organic material you’re looking at, or it’s the products of the incomplete oxidation of suspended organics, and it means you’re not oxidizing near’ well enough in your high-load pool.
Notwithstanding such causes as the nearby rice-field burning or the neighboring dusty, windy construction site, poor oxidation in any pool water will eventually allow cloudiness to develop. Remember that the filter's job is to handle the big particulate and the non-oxidizables; your chemical oxidizer has the far greater job in producing polished water than the mechanical straining performed by the filter.
The chlorine product (or other “oxidizer”) must handle the organic solids introduced into, and suspended in, your pool. If your ORP is impaired in any way, by high pH, dominance of chloramines or excessive stabilizer, the oxidation process may be slowed by an order of magnitude (1/10th!) or more. Cyanuric acid alone, for example, can reduce the equivalent ORP of 1 ppm “free” chlorine to that of an un-stabilized .2 ppm. And that’s at only 20 ppm CYA! More stabilizer? Enjoy your cloudy pool.
So I hope your pool is automated by a device that measures and controls the oxidation potential of whatever sanitizer you’re feeding. Setting a value of 780 to 800 mV will cause a feed of, well, whatever it takes to oxidize those suspended organics and clear up that pool. And go easy, please, on that Cyanuric Acid stabilizer!
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