14 Things you Need to Know About Swimming Pool Maintenance and Automation
Before you read this, we apologize in advance for it's length and the level of technical detail. That said, the devil is in the details and we wanted to be comprehensive.
1. Pools are expensive, but most lack technology Swimming pools are significant investments. 80% of the pools in Litchfield County cost between $50,000 and $150,000 to build. That same investment buys a luxury car somewhere between a BMW 3-series and a Porsche 911 Turbo. Given the cost, one would expect either platform – the pool or the car – to operate flawlessly for many years. Equally important, one would expect that the technicians working on either platform would be highly trained and proficient. Unfortunately, this is rarely the case.
Modern cars require sophisticated computers to manage engine functionality and meet emission standards set by the EPA. These regulations not only reduce pollution, but significantly improve car reliability. On the other hand, Connecticut has a trivial licensing requirement for pool technicians, and there are no health department standards that need to be met for residential pools. Accordingly, most pools do not use any form of automation to manage their water chemistry and the job rests on the weekly pool guy. The result is that most (if not all) pools can:
harbor waterborne illness
have a strong "smell of chlorine"
cause eye, skin and respiratory irritation
eventually require re-surfacing in order to fix rough plaster
But none of this needs to happen.
2. Computers for Pools Cost effective systems exist today to monitor and manage pool chemistry, fully automatically, on a 24x7 basis. These systems can also control temperature, lighting, and other pool/spa features. Better still, these systems can be conveniently monitored or adjusted via a smartphone and integrated into a home automation system.
3. Saltwater vs Freshwater pools Let's first address a common misconception that saltwater pools are better because they don’t need chlorine. The truth is that all pools require some form of chemical disinfectant in order to kill the viruses, bacteria, algae, and parasites that make pool water harmful. The chemical of choice is chlorine because it's highly effective, inexpensive, and safe. In most fresh water pools, chlorine tablets are placed in the water flow where they dissolve slowly to provide a stream of disinfectant. Saltwater pools work differently – if you remember back to high school chemistry - regular "table salt" is also called Sodium Chloride, a molecule comprised of Sodium and Chlorine. Saltwater can be run through a device called a "chlorine generator" to extract the chlorine from salt. Both freshwater and saltwater pools require equal amounts of chlorine, but there is little need to add chlorine to a saltwater pool because it makes its own.
4. How much chlorine is needed in the average pool? The quick answer is between 2 and 4 "parts per million" (or "ppm") with a target of 3 ppm for a pool and 4 ppm for a spa. But when added to a pool, chlorine eventually disappears; some of it evaporates into the air and some of it is "consumed" when it works as a disinfectant. The evaporation is expedited with sunlight, and after about three hours of bright sunshine, almost all of the chlorine is gone.
5. Free Available Chlorine and Bound Chlorine Free Available Chlorine (also known as "FAC" , "FC" or "Available Chlorine") is the amount of chlorine in the pool that is available to be used as a disinfectant. The target value for this is the 3 ppm level referenced earlier. A second term is "Combined Chlorine" (also known as "CC" or "Bound Chlorine") and it's the byproduct of the disinfection process. Bound chlorine is chlorine that is still present in the water, but it has been "used up" and is no longer available to act as a disinfectant. The disinfection process is quite complex, but essentially Chlorine binds itself to a wide group of ammonia-based chemicals (called amines) that include sweat, urine, and "amino acids". Amino acids (also known as amines) are the building blocks of proteins that are found in all living organisms. When chlorine and amines meet in the pool water, the chlorine binds to them to form new set of chemicals called "chloramines". The chlorine binding process (chloramination) is what kills viruses, bacteria, algae, and most microorganisms. Chlorine also binds to amines found in urine and sweat. As one would imagine, the bigger the bather load, the more sweat and micro-organisms are added to the water. Accordingly, FC goes down and CC goes up. Just so you know, bigger pool contaminants (like insects, frogs, people, etc.) are not impacted by the chlorine in a pool.
6. The “chlorine smell” misconception When bathers "smell like chlorine" this isn’t because there is too much chlorine in the pool; it actually means there is too little. Humans can't smell chlorine particularly well at 3 or 4 ppm. In fact, even when there is too much chlorine in the pool (say 6-10 ppm), it doesn’t smell particularly strong. However, humans are very sensitive to chloramines and can easily detect them at a level of 0.05 ppm! That "pool smell" is actually caused by an excess of chloramines in the water: this is indicative that the Free Chlorine has been used up and too little remains. Chloramines are the primary cause of "red eyes", skin irritation, and even respiratory irritation. The target level of chloramines (CC) in pool water is zero and remediation is suggested if the level reaches 0.2 ppm.
For those who really want a deeper understanding of this - there are three "species" of chloramines found in pool water. The first species produced in the disinfection process is called monochloramine. These have the chemical structure NHCl and they are actually a disinfectant with little or no smell. But if the amount of contaminants increase more and FAC decreases, then some of the monochloramines are converted to dichloramines (NHCl2). This species smells bad and has negative effects on people. The process can head further downhill when dichloramines are converted to trichloramines (NHCl3) - a particularly noxious chemical. If the pool gets to the stinky stage, then it likely has too much di- and trichloramines and needs to be "shocked".
7. Pool Shocking Pool shocking is a term used when the level of FAC is raised from the normal 3 ppm to a much higher level by adding lots of chlorine. When pools are opened in the spring, it's not uncommon to raise the level FAC to between 20 and 30 ppm. But when pools are properly maintained with a constant FAC of 3 ppm, “shocking” is never necessary. The method for maintaining a constant 3 ppm is achieved by detecting decreasing FAC and triggering the addition of more chlorine. Low levels of chloramines will simply decompose in the presence of chlorine at 3 ppm, and evaporate into the air as ammonia. However, in a mismanaged pool – one where the chlorine levels remain too low for too long , di- and trichloramines will build up. When this happens, increasing the amount of chlorine back to a normal 3 ppm might not be sufficient to break down the excessive chloramines. The remedy is to raise the level of Free Chlorine (FC) at a point 20 times greater than the level of Combined Chlorine (CC), and keep it there for several hours. This is called "shocking" or "super chlorination". So, if the CC rises to 1 ppm, then the FC level should be raised to 20 ppm – a level far too high for swimming.
8. Feedback Loop Until the mid-1800's, homes were all heated by coal or wood stoves that couldn’t be easily controlled; they were either on or off, and room temperatures fluctuated wildly. Then, almost 100 years ago, along came the thermostat. You certainly have several in your own home and you might even have one that can be controlled with a phone. By integrating the thermostat to a furnace, interior temperatures could be accurately and constantly controlled. This mechanism is called a "feedback loop" with one device “measuring” something and another device “producing” something based on the measurement.
In all likelihood, your pool is like a stove from the 1800's – with no chlorine measurement system and no way to properly dispense it in proportion to actual need. Most likely you have chlorine tablets that sit in the water stream or even a chlorine generator dispensing it on a timer. Neither of these are reliable as the chlorine levels will never be correct; excessive some times and insufficient at others. This is detrimental to the swimming experience and potentially a health risk.
9. Chlorine isn’t the only thing to worry about. If you remember back to high school chemistry, pH is the measurement of acidity versus alkalinity. For pool sanitation, maintaining proper pH is as critical as maintaining proper FC. The primary reason relates to the efficacy of chlorine in sanitation. The secondary reason relates to ensuring the pool surface doesn’t get ruined in concrete and gunite pools.
10. pH and chlorine sanitation When chlorine is added to water, two chemicals are formed in different amounts. The first is called hypochlorous acid (chemical symbol HOCl). The second is the hypochlorite ion (chemical symbol OCl-). The first is highly effective as a germicide and will kill bacteria, viruses and parasites. The second is much less effective and will not kill viruses or parasites. The ratio of these two chemicals in your pool is determined by the pH of the pool water. At a pH of 7.0, the ratio of HOCl (the strong one) to OCl- (the weak one) is about 80:20. At pH 7.5 it's 50:50, and at pH 8.0 it's 20:80. For the purposes of sanitation, a lower pH is clearly desirable.
11. When the pH is off, your pool surface can be destroyed. A lot of things can dissolve in water – sugar, salt, gases, chlorine, etc. Water can hold quite a bit of "stuff"; a single cup of water can dissolve almost a pound of sugar. Water can also hold quite a bit of dissolved calcium - a chemical that's found in a wide variety of things (limestone, milk, bones, etc.). It is frequently found in drinking water, and the quantity of it is referred to as "hardness". But in gunite pools, the plaster coating is mostly made of calcium, and it too can dissolve into the pool water. What determines how much is really complex (and an explanation will certainly bore you to tears), but suffice it to say, if the pH is low and/or the temperature is high, calcium will be pulled out of the plaster and will dissolve in the pool water. This is known as "etching" and creates tiny holes in the pool surface; somewhat like a pumice stone. So, for the longevity of your pool surface, a low pH is clearly not desirable. Similarly, if the pH is too high, some of the calcium that is already dissolved in the water can be deposited back onto the pool surfaces as sharp crystals (known as limescale, or simply scale). The "Saturation Index" or "SI" is used to determine which way calcium will move. A negative number means that your pool is etching. A positive number means scale deposits. The determination of SI is beyond the scope of this page, but it is highly dependent on pH. As with chlorine, if the pool equipment cannot measure and control pH, then the plaster is at risk. This doesn’t impact health, but fixing the plaster means draining, resurfacing, refilling the pool, and then adding back all of the necessary chemicals. This costs between $5,000 and $10,000. Poorly managed water can also lead to premature failure of the heater; another $3,000 (or more). Note that these problems occur slowly – so it will not become apparent in one or two seasons. But when you ask your pool technician why this has occurred, you can be assured that it will not be their fault!
12. Reality Check Unlike the BMW or Porsche technician, the person responsible for your pool is not highly trained. Unlike a luxury car, which has a host of sensors and a built-in computer to monitor itself continually, your pool probably has nothing to manage its chemistry. Most pool builders don’t suggest automation early on in the process, or at all. Most believe that computer-controlled automation will eat into the profits of their seasonal maintenance business. This is a specious argument as most of the maintenance cost relates to vacuuming, cleaning the filter and baskets, and not to balancing the water. The other problem is that pool builders are not engineers, and the automation equipment needs to be properly set up, calibrated and connected to the internet in order to work. When something goes wrong, the pool builders are poorly equipped to diagnose and fix networking, computer or sensor issues.
13. There is a better way Automation equipment can manage your pool's pH, chlorine levels, temperature, pump, and lights. It also conveniently works over the internet, so you can control it from a phone, tablet, or PC. The chemistry still needs to be checked manually (to ensure accuracy) and the pool still needs to be cleaned, so you still need the pool technician to come over. However, when automated, your chemical costs will be reduced and the pool will be perfectly balanced every time you swim. No more chlorine stink, red eyes, or itchy skin. Your plaster will be happy too. In short, pool automation leads to a significantly better swimming experience, reduces the weekly chemical bill, and saves you money on long-term maintenance.
14. Automation costs vary Depending on what you already have in place, a reasonable budget to automate is around $6,000 for the equipment and installation services. You will need to hire a company that can ensure you have a properly configured network, who understands the setup and configuration of the software, and has the engineering skills to make it all work together. Cagenio is that company.
Let Cagenio make your life easier. Please call or email us for an appointment.