Posts Tagged ‘David Knighton’

pH, Buffer, Total Alkalinity, Chlorine and PoolNaturally Plus

August 23rd, 2012

pH, Buffers, Total Alkalinity, Chlorine and PoolNaturally Plus

Everything You Wanted to Know And Were Afraid to Ask

By David R. Knighton, M.D. and Vance D. Fiegel, B.S.

Co-Founders of Creative Water Solutions, LLC



It’s all about hydrogen ions and water.  Hydrogen, you remember, the most abundant molecule on earth, is in the upper right-hand corner of the periodic table of elements.  It is just one proton and one electron.   Two hydrogen molecules combine with one oxygen molecule to form water.   The hydrogen ion (H+) in water has a positive charge; the mirror image chemical is the hydroxyl ion (OH-) that has a negative charge.  These two ions are like a teeter-totter.  When one is up, the other is down.  An acid has a high concentration of hydrogen ions and a low concentration of hydroxyl ions.  A base is just the opposite.  Put an acid and a base together carefully because they react with vigor to make water and release a lot of energy.

To understand pH, buffers, total alkalinity, and chlorine in any body of water like a pool, spa, pond or drinking water, you have to understand hydrogen ions.


The term pH refers to the concentration of hydrogen ions in water.  It is a logarithmic, not a linear, scale.  Higher numbers refer to a decrease in the concentration of hydrogen ions while lower numbers reflect a higher concentration of hydrogen ions.  That means that when the pH changes from 6 to 7, the actual change in the concentration of hydrogen ions is 10 fold lower, and a pH change from 6 to 8 is a 100 fold lower.  Therefore, seemingly small changes in pH mean large changes in hydrogen ion concentration.


Buffers are molecules that can combine with and release hydrogen ions.   Many different molecules can act as buffers.  The most recognized buffer in the pool and spa industry is bicarbonate.  Depending on the pH of a solution, it can either release hydrogen ions in the water, or combine with hydrogen ions in the water to remove them from the solution.   Many other molecules also act as buffers.  Many amino acids and proteins made from amino acids are buffers.  Long chain sugar molecules can also act as buffers.  Buffers stabilize the pH of a solution over a range of hydrogen ion concentrations and are most effective when the pH of the solution is near the pKa of the buffer.  Buffering capacity is also dependent on the concentration of the buffer.  Buffers perform best over different pH ranges.   Pick the pH you want, add the right buffer, and the pH of the solution will stay stable over the range of that buffer.  It is a chemical version of balance.

Bicarbonate is also one of the buffer systems in your blood.  As the hydrogen ion concentration fluctuates in our blood, the bicarbonate and proteins in our blood combine with hydrogen ions if there are too many, or release hydrogen ions if there are too few, to keep the pH stable.  It works well at a pH of 7.4 (that’s the pH of our blood when we are healthy) because our bodies can rapidly control the CO2 levels through a process called physiological buffering.  It is not, however, an optimal buffer for recreational water systems.  The bicarbonate buffer system has a pKa of 6.1, which is quite far from the operating pH of 7.2-7.6 typically seen in swimming pools.  As stated above, buffers are most effective when the pH is close to the pKa.  This would explain why controlling and maintaining a stable pH can be so difficult.  Because the operating pH is more than one unit from the pKa of the buffer, the system is living on the edge of the ability of the bicarbonate buffer system to work effectively.

Why is a bicarbonate buffer system used in pools if there are better options?  The first reason is that it is the buffer system that exists in tap water (and what is measured when we measure alkalinity).  The second reason is that the chemicals used to control pH are relatively inexpensive.  The third reason is that the use of a more appropriate buffer, with the right pKa (i.e. a phosphate buffer system), would require the use of additional chemicals, increasing cost and the complexity of the aquatic water system.


Total Alkalinity vs. Alkalinity

This confused us when we first started paying attention to the pool and spa water chemistry terminology.  In chemistry, we learned that alkalinity is the absence of hydrogen ions resulting in a high pH.  When we read the indicator strips and saw total alkalinity we thought we were measuring the hydroxyl ions in the water.  A lot of hydroxyl ions mean a low concentration of hydrogen ions or an alkaline solution.  These readings didn’t make sense, so we  asked a dumb question and Tom Schaffer from US Aquatics, Inc. (he is a CPO instructor and has 30+ years industry experience) told us that total alkalinity, as viewed in the pool and spa industry, is a measure of bicarbonate buffer.  Low total alkalinity reflects a low level of bicarbonate buffer in the water solution; it does not reflect the alkalinity (concentration of hydroxyl ions) of the solution.

Tom also told us about pH bounce when the bicarbonate level gets too low.  This made sense to us once we knew what total alkalinity means.  If there is too little buffer in a solution, adding hydrogen ions (acid) overwhelms the buffering capacity and will result in a meteoric fall in pH.  This occurs if bicarbonate is the predominant buffer in the solution and  the total alkalinity goes below 60.  That’s why many state regulations require pool operators to keep total alkalinity above 60, so there is enough buffer to keep the pH stable.

If the total alkalinity is high, like in some source water, then there is so much bicarbonate that it is very difficult to get the pH to go down or to increase the number of free hydrogen ions in the solution.  If you add enough hydrogen ions by adding acid, then a balance can be achieved to keep the pH stable.   Add more bicarbonate buffer and you will have to add more acid to balance the solution.  A high total alkalinity can also affect the use of CO2 to increase hydrogen ion concentration thus lowering the pH of the solution.  To understand this effect we have to understand the chemistry of CO2, water, bicarbonate and acid.  CO2 alone is not acidic.   When CO2 is dissolved in water, a slow chemical reaction occurs to form carbonic acid.  Carbonic acid then gives off hydrogen ions and forms bicarbonate.  All these reactions are in equilibrium and occur at different rates.   If the bicarbonate level in a pool is very high, then the reaction to form hydrogen ions from carbonic acid is driven in the opposite direction.  As a result, adding more CO2 cannot increase hydrogen ion concentration and simply off gases from the pool water into the air without changing the water’s hydrogen ion concentration.

pH and Chlorine

When chlorine (or bromine) is added to the mix, the chemistry becomes more involved.  We will talk about hypochlorous acid, not chlorine.  Hypochlorous acid is the ion formed when chlorine is added to water.   Hypochlorous acid is also the oxidative molecule that kills bacteria, algae and cryptosporidium.   The ORP (oxidation reduction potential) probe measures the oxidative potential of the water.  Since hypochlorous acid is the major oxidizer in pool water, the ORP is used to constantly monitor the pool water and to add chlorine when the ORP goes below a set level. Hypochlorous acid is very reactive, so it combines with a lot of other molecules to form new molecules.  Hypochlorous acid changes when the pH goes above 7.6.  It basically morphs into a form that doesn’t react anymore, so it doesn’t kill anything.

Remember, because the scale is logarithmic, that a change in pH from 7.3 to 7.6 results in one- half  the concentration of hydrogen ions.  This is a very large change.  Hypochlorous acid works a lot better at pH 7.2 to 7.4.  That’s why keeping the pH at this level reduces the amount of chlorine needed to maintain a desired free available chlorine level.

pH, total alkalinity, buffers and PoolNaturally Plus

PoolNaturally Plus contains the leaves of one species of Sphagnum moss.  PoolNaturally Plus affects the pH, buffer and total alkalinity of the water it touches.   If you test the water in a wetland bog that contains Sphagnum moss it will be acidic (high hydrogen ion concentration).  Sphagnum moss leaves and therefore PoolNaturally Plus, have a cation exchange system that binds positive ions, like iron and calcium, and pumps hydrogen ions into the water causing the water to become acidic.

During testing in pools and spas, we also found that PoolNaturally Plus stabilized pH and lowered total alkalinity over time.  What was interesting is that even with the lowered total alkalinity we found no pH bounce or pH instability at all.  This prompted us to allow the total alkalinity to equilibrate and see what happened.  To our surprise, and the pleasant surprise of the pool owners and operators, they didn’t need to add bicarbonate to elevate total alkalinity to prevent pH bounce.  Using PoolNaturally Plus, we recommend keeping the pH between 7.2 and 7.4 and letting the total alkalinity equilibrate to a steady state over time.  This results in a net decrease in the bicarbonate and acid needed to maintain stable water.

Using CO2 with PoolNaturally Plus works very well.  Because the total alkalinity is low, there is a low concentration of bicarbonate in the water.  This facilitates the conversion of CO2 to carbonic acid and then to hydrogen ions and bicarbonate.

We also documented a decrease in chlorine delivered to the pool needed to maintain a stable free available chlorine (hypochlorous acid) level.  The oxidative state of the water also became stabilized as measured by ORP.   The end result is stable water using less chemicals.



December 1st, 2011

Swimming Performance and Disinfection Byproducts:  Biocides, Biofilm and PoolNaturally® Plus

By David Knighton MD

Co-Founder and CEO of Creative Water Solutions and PoolNaturally® Plus



Walk into a building with a pool and you can instantly tell it’s there by the smell.  No matter how big the building, small the pool, or robust the heating and ventilation system, that characteristic “chlorine” smell is there.  If you are like me, a few minutes of exposure to the smell will bring tightness to my chest, itching to my eyes, and after about 20 minutes a light headed feeling.  Go outside and it all goes away in about an hour.  Swim and it can take days to return to normal.  Competitively swim or swim daily and you probably get so used to the air you become acclimated to the irritation of disinfection byproducts (DBP).  In the past few years, a lot of research has defined what causes this smell, what effect it has on swimmers, and what can change the creation of DBP’s so the pool becomes a “you don’t know there is a pool until you see it” experience.  

How are DBP’s formed?

 DBP’s are formed when chlorine, bromine or any halide molecule used to kill bacteria in the water, combines with biologic molecules that contain carbon and nitrogen.  The most prevalent molecule in the swimming environment is urea from urine and sweat.  Urea undergoes chemical changes in the pool and combines with chlorine or bromine to form over 30 different DBP’s.  Some of these molecules stay in the water and others are volatile so they diffuse into the air above the water and eventually into the entire building.  The act of swimming actually increases the concentration of DBP’s by churning up the water and increasing the concentration of these molecules in the air. 

What Effects do DBP’s have on people?

We know a lot about the effect of one DBP – chloroform – since it was the most commonly used anesthetic for decades.  The fancy name for this class of DBP is trihalo-methane (THM).  There are many different THM’s with different effects on people, just like there are many different types of DBP’s that have different effects on people.  We will look at chloroform and trichloronitrate.

Chloroform inhaled at a concentration of 10,000 ppm puts you to sleep.  Prolonged exposure at this very high level will kill your liver, depress your heart function and kill you.  In human volunteers, exposure to 4,100 ppm causes serious disorientation and 1,000 ppm causes dizziness, nausea, fatigue and headaches.  Prolonged exposure to as little as 10 to 200 ppm can cause liver enlargement and effects on the central nervous system.  For a reference, we have measured THM concentrations in commercial indoor pools in the 2 – 3 ppm range. 

Application of chloroform to the skin causes redness of the eyes and itching of the skin.  One study of people exposed to low levels of chloroform in their drinking water showed a correlation between chloroform concentration and rectal and bladder cancer.  In fact, an international health agency classifies chloroform as a carcinogen for humans.

Other studies, especially from Europe, document the effect of trichloronitrate on swimmers.  They conclude that this DBP is related to reactive airway disease or asthma in people who swim frequently.  Another study shows that DBP’s are associated with changes in DNA in urinary bladder cells that correlate with an increased risk of cancer.

To summarize, DBP’s not only smell bad, they irritate your skin, eyes and lungs; cause central nervous system changes such as dizziness and headaches; cause fatigue; and with prolonged exposure are potential carcinogens.

How do DBP’s affect swimming performance?

Any athletic performance is determined by muscle contraction.  Muscle contraction is an energy consuming activity that is related to oxygenation of the blood and blood flow to and from the contracting muscle.  Oxygen is used along with blood delivered nutrients to produce energy so the muscle cells can contract and propel the swimmer through the water.  Oxygen is delivered to the blood through the lungs as we breathe.  Oxygen is then carried by our red blood cells to all tissues in our body including muscles, by blood flow.  Blood flow depends on our heart to pump the blood and arteries to carry that blood to our exercising muscles.

At rest, our muscles require very little blood flow and oxygen.  As we start to exercise and use our muscles to propel us through the water, they consume all the oxygen and nutrients in the area, then tell their arteries to dilate and send more blood.  That causes our hearts to beat faster to supply more blood for the dilated arteries and that eventually causes us to breathe faster to deliver more oxygen to our lungs.  A big part of athletic training, is to maximize this energy transport system from air to muscles.  The more we exercise, the better the system works.  The better the system works, the more we can exercise.

DBP’s affect performance in a number of ways.  First, the air just above the water is what a swimmer inhales during swimming.  That air has the highest concentration of DBP’s.  The amount of oxygen in air follows the rules of physics.  The higher the concentration of DBP’s, the fewer oxygen atoms in the same amount of air.  So the swimmer in a pool with high DBP’s needs to move more air in and out of their lungs to remove the same amount of oxygen as a swimmer in a pool with lower DBP’s.

DBP’s like trichloronitrate cause lung irritation and narrowing of the tubes that bring air into our lungs.  Because of the narrowing, less oxygen gets to the microscopic areas of our lungs where the delivery of oxygen to the blood occurs.  Therefore, we need to move more air to extract enough oxygen for our exercising muscles.  One result of this lung irritation is the use of drugs, called bronchodilators, that open up the airways and others, that control the inflammation caused by the irritating DBP’s.  This asthma is a significant problem in many competitive swimmers.

Like most diseases, some people are more sensitive to DBP’s than others. 
Those swimmers who are sensitive to DBP’s have to work harder to provide adequate energy for their contracting muscles than those who are less sensitive to DBP’s irritation.

Performance and conditioning is all about maximizing oxygen extraction from the air, blood flow to the muscles, and removal of waste products from the exercising muscle.  DBP’s play a significant role in oxygen concentration in the air; delivery of air to the blood, and pumping of blood to the muscles.  Along with the other health effects of chronic exposure to DBP’s and the uncomfortable irritation they cause, swimmers should do everything possible to minimize the concentration of DBP’s in their pools.

What can swimmers do?

Since urea is one source of nitrogen containing bio-molecules that form DBP’s, swimmers can reduce their formation by not urinating in the pool.  Sweat is another source of urea that cannot be easily controlled since training causes increased sweating.  I’ve talked to many competitive swimmers who tell me they don’t want to stop their training to go to the bathroom to urinate or that their coaches won’t let them take a break.  Changing this would help create a more healthful environment for every swimmer, coach, lifeguard, and spectator.

What can facilities can do?


To understand the role of ventilation in this problem, we need to remember that DBP’s are at their highest concentration on the surface of the water.  This is the boundary layer where there is little air movement.  Traditional ventilation brings outside air inside, warms it up or cools it off depending on the temperature, and then moves it through the building, eventually pushing the air back outside.  This is a very expensive process.  Moving more air from the outside and through the entire space of the natatorium doesn’t address the area of the pool where DBP’s are in their highest concentration.  Increasing the air movement at the surface of the pool does result in a decrease in the concentration of DBP’s.  Paddock Evacuator Company’s Chloramine Evacuation System achieves this by a system that moves the air across the boundary layer and moves it outside.

Water treatment

Water disinfection and formation of DBP’s is a classic “rock and a hard place” situation.  Chlorine and bromine are very effective and efficient killers of swimming (planktonic) bacteria and algae.  They accomplish this through their chemistry.  They are very reactive with other atoms and molecules.  This reactivity oxidizes proteins and sugars in the cell wall of bacteria and algae, but also reacts with carbon and nitrogen containing compounds to form DBP’s in the water and air.   It is the main way we control bacterial growth in most water systems.  Even treatment systems, such as salt pools, control bacterial growth with chlorine.  You don’t have to add the chemical, a reactor in the pool creates bio-reactive chlorine from the chloride ion in common salt.

When we started treating commercial pool water with PoolNaturally® Plus we found that the air quality in the pool area improved in a couple of days and the air in the entire facility was significantly improved after a week of treatment.  Over time our customers starting saying that the only way you know there is a pool in the building is to see the water.  Swimmers, coaches, lifeguards, and pool patrons all reported less eye, skin, hair, and lung irritation.  After a swim meet in one of our pools, many swimming teams demanded that their facility add PoolNaturally® Plus.

To measure the effect of PoolNaturally® Plus on DBP concentration, we did a study with a fitness club to measure the THM in the air above the pool surface and the water in their two indoor pools (75,000 and 86,000 gallons).  We measured levels weekly, for two weeks before PoolNaturally® Plus was introduced and then about every other week for 33 weeks. They have a high bather load and use chlorine for disinfection.  We measured a steep decline of THM in the water resulting in 75% reduction in 33 weeks.  In the air above the pool the chloroform concentration was decreased by 55%.  The air quality improved just like in our other indoor facilities.

How does PoolNaturally® Plus affect DBP production?

The quick answer is we don’t know.  We do have a hypothesis.  PoolNaturally® Plus is made from Sphagnum moss leaves.  In our laboratory, over the past 8 years, we have shown that PoolNaturally® Plus inhibits biofilm formation.  Biofilm is a slime like substance that protects bacteria that adhere to the pool or filter surface.  In fact, most bacteria prefer to adhere to a surface and cover themselves in biofilm, than to swim unprotected in the water where chlorine can kill them.  We think the unique environment inside the biofilm helps convert urea and other organic compounds into DBP’s.  We postulate that inhibiting biofilm reduces the production of DBP.  The product could also have a direct effect on the DBP produced in the pool.  We know the concentration is significantly decreased.  We don’t quite yet know how.

PoolNaturally® Plus and swimming performance

We know competitive swimmers like training in water conditioned with PoolNaturally® Plus.  We know that swimmers with asthma report that they don’t use their inhalers when they swim in outdoor or indoor pools where water is treated with PoolNaturally® Plus.  We also know that lifeguards and aquatic professionals report fewer respiratory problems working around pools with PoolNaturally® Plus.  We don’t know if their training and eventual performance is improved, and it will take time and study to know if the reactive airway disease, DNA changes and other health effects of DBP’s are improved.


  1. Use of chlorine and bromine as disinfectants in pools produces disinfection byproducts that have significant health and performance effects.
  2. DBP’s, such as chloroform, other THMs and trihalonitrates irritate people’s eyes, skin, lungs, and central nervous system.
  3. Pool water conditioned with PoolNaturally® Plus reduces the “chlorine smell” in treated pools and resulted in a 75% decrease in THM in commercial pool water and 55% reduction in natatorium air.
  4. Patrons of pools treated with PoolNaturally® Plus report significantly less eye, skin and lung irritation.


Articles about asthma and chlorine:

Chloroform and effects on humans:

THMs and bladder and colorectal cancer:

More about Paddock Evacuator Company’s Chloramine Evacuation System:

More about Creative Water Solutions’ PoolNaturally® Plus system:

Dramatic New Benefit of Sphagnum Moss Water Treatment Method Discovered

November 2nd, 2011

Creative Water Solutions ( — CWS) announced October 19th, 2011 that it has filed for a patent under the heading —Use of Moss to Reduce Disinfectant By-products in Water Treated with Disinfectants.  The patent will cover all of its products that use the moss-based water treatment, including PoolNaturally®, PoolNaturally® Plus, SpaNaturally®, and SpaNaturally® Plus.

After a 33-week scientific study of two large, commercial indoor swimming pools in the Twin Cities area, CWS measured the levels of DBPs and VOCs and the impacts of the resulting from the use of Sphagnum moss. The test found that its sphagnum moss product, PoolNaturally Plus, dramatically reduced DBP and VOC levels, reducing odor, decreasing chemical smells and their unpleasant side effects on swimmers, lifeguards, maintenance and other staff.

 DBPs are created in pool systems through the chemical reaction of the chlorine disinfectant with organic matter in a pool, or spa. Many DBPs are toxic compounds, such as trihalomethanes (THM) and halocetic acids, and are the main source of the odor and health issues associate with pool facilities and use.

“Our tests found significant DBP reductions and air quality improvements, clearly establishing another significant benefit of the PoolNaturally-Plus system.  THM’s, such as chloroform, are created in the water and then move into the air of a facility. The demonstrated reduction of THM’s in the pool water correlates nicely with the reduction of chloroform in the air and the subsequent increase in air quality” says Vance Fiegel, CWS’s Chief Scientific Officer and co-founder. “Our data shows that besides reducing the amount of chemicals needed to treat water (and lessening irritants to swimmers, maintenance time and corrosion of motors and liners) the moss is also providing measureable air quality benefits:

  • THM levels plummeted between 73-80% once the moss was introduced into the pools. 
  • Chloroform showed a 55% reduction in the air of the pool facility.

  According to Dr. David Knighton, MD, CWS President, CEO and co-founder, the scientific data reflects the anecdotal reports the company has consistently been receiving from management and staff at other indoor swimming pools.

 “We are very excited to discover yet another benefit of this miracle plant and innovative water conditioning agent,” Knighton notes. “Our customers at many college pools and those at indoor water parks like Chaos, located in Eau Claire, Wi., can corroborate our most recent scientific discoveries about air quality enhancement with the personal evaluations and experiences of those who work daily in an enclosed swimming environment.”

Knighton cited a representative case study recently done at Chaos with Barry Thompson, a retired Navy Master Chief who helped design the facility and currently is its chief operator:

·         At most water parks, chlorine disinfection by-products permeate the air at a park’s indoor and outdoor areas: “You can usually smell the heavily chlorinated water in the parking lot. At Chaos you don’t get that smell inside or outside — or on your clothes and in your hair after you leave,” Thompson says.

·         Lifeguards are reporting a dramatic reduction in headaches from chloramines and disinfection byproducts due to the reduced usage and the increased efficacy of chlorine to deal with bacteria producing agents and organic material in the water.

·         The lifeguards and other staff are reporting less absenteeism thanks to a more natural, less chemical work environment.

For more information — or to interview Vance Fiegel or Dr. Knighton — please contact Martin Keller, Media Savant Communications Co., 612-729-8585,

Aquatics International recognizes CWS’ Knighton in Power 25 Reinventors

February 15th, 2010

Creative Water Solutions President and co-founder David Knighton, MD has been recognized by Aquatics International magazine as one of their Power 25 Reinventors.  Successful testing of sphagnum moss-based PoolNaturally Plus at Highland Park Aquatic Center in St. Paul, MN, during the summer of 2009 marked CWS’ entrance into the commercial side of the aquatics industry. Read more at Aquatics International.

Tommy Mischke Interviewing CWS’s Dr. David Knighton Today at 2pm

September 4th, 2009

Dr. David Knighton, co-founder and President of Creative Water Solutions, LLC will be interviewed at 2p today by legendary radio personality Mischke — tune in online at this link


We’ll be Twittering during and after the show – hashtag #poolmoss

Preliminary Results Announced By City of St. Paul and CWS

August 17th, 2009

SAINT PAUL — Mayor Chris Coleman, Creative Water Solutions, LLC President and CEO David Knighton, MD,  and Parks and Recreation Director Mike Hahm will unveil preliminary results of the nation’s first public-pool sphagnum moss-based water treatment system installation at 11a on August 17 at Highland Park Aquatic Center (see link for more about this pool).  The pilot project was undertaken with the innovative Minnesota-based company, which has already demonstrated the moss-based system’s effectiveness in residential pools and spas (PoolNaturally and SpaNaturally, respectively).

“It’s a completely different pool!  My eyes and the kids’ eyes didn’t get red, the water didn’t smell of chlorine and it was a lot softer feeling in general,” said 19-year-old Mary Schmidt, a regular weekly visitor to the pool as a summer nanny.  “I love it!”

To see the full media release, please visit this link.