Drought vs. El Nino
Water Chemistry for a Crazy Climate
By Terry Arko
Water is an amazing, mysterious and powerful element. To understand the capabilities of water and its effect on swimming pools, it is vital to understand how water travels throughout our world. The water cycle is a continuous loop of various methods of which water continuously transforms and renews itself.
As water transforms and travels, it is subject to the environment in which it passes. Fog, for example, rises from the ground and passes through the surrounding air. As it does it picks up whatever is in the air, whether it be smoke, dust or car exhaust. Snow on the ground can pick up contaminants and bacteria. When the snow melts and turns into liquid those contaminants and bacteria can be transported into a nearby stream and river and even end up in source water.
In Milwaukee in 1993 one of the largest outbreaks of cryptosporidium in drinking water was found to be the result of contaminated snow -melt feeding into Lake Michigan. Water moves about this world in lakes and rivers. It takes the form of ice, snow, fog or rain. It is the great absorber and transporter of whatever it comes in contact with. In today's crazy climate, the challenges of source water contamination in swimming pools can be many.
The Evaporation Problem
There are some studies that suggest that the annual evaporation rate in Southern California ranges from 6 to 8 feet. That means that the entire contents of an average swimming pool can be removed by evaporation in a year. When water evaporates from a swimming pool, the water in the pool is changed from its liquid state into a gas or water vapor that travels back up into the atmosphere. When water vaporizes only pure water leaves the pool. So, as pure water leaves the pool it also leaves behind more dissolved solids that contribute to total dissolved solids (TDS).
There are two environmental factors that will increase the acceleration of evaporation: temperature and humidity. If you placed a pot of water on a table in a cool and humid environment, it could take weeks to months for the water to evaporate. However, if you place that pot on the stove and turn the heat on it will evaporate in a matter of minutes. The more heat the faster evaporation occurs. Also, when you combine heat with dry air then the water will vaporize more quickly. This is why evaporation is a big problem during times of drought when the air is warmer and drier. This accelerated evaporation during times of drought means that the buildup of solids in the pool water will also increase leading to higher TDS, calcium hardness and pH. This will mean that more acid will be needed to maintain the proper water balance during these drier hotter days.
Also, as TDS increases, the effectiveness of chlorine sanitizer will be reduced. In fact a TDS that is 1500 ppm over the startup water can lead to a 50 percent reduction in the effectiveness of chlorine as a sanitizer. Unfortunately, if a state or principality has declared an extreme drought then draining of pools can be restricted. If the pool can't be drained and diluted to lower the TDS this means that 50 percent more chlorine will need to be added to the pool just to keep a residual of free available chlorine (FAC).
Proactively reducing organic contaminants by weekly shocking and the use of a natural-based polymer clarifier can help to slow the buildup of these solids. Also, since phosphates are a part of TDS using a weekly phosphate removal will help to keep levels lower.
Lower Water Levels
Another problem during drought times is that the groundwater gets used up more quickly. Groundwater is what comes from rain that permeates through the soil and then makes it way below ground through cracks and fissures. During periods of drought as groundwater levels go lower, this leads to more contaminants in the source water that can lead to higher total hardness, minerals and metals.
According to the National Groundwater Association (NGWA) about 44 percent of the United States population gets its drinking water from groundwater. The concentration of metals such as copper and iron increase in deep groundwater. Stain and scale inhibitors and metal sequestering treatments will need to be used particularly in areas with well water.
Also as groundwater levels drop, chloride levels increase from an influx of brackish water. This leads to more particulate and higher dissolved solids. The use of shock treatments and natural polymers to floc and remove these to the filter can help. Nitrates can be a big problem in groundwater as well, and that can have a direct effect on FAC in pool water. Nitrates in swimming pool water create chlorine demand that devours FAC levels. Again, heavy shocking may help here, but draining and using trucked-in water that is free of nitrates would be the best solution in these cases.
The Overnight Change of Make-Up Water
Recently in the East Bay area of Northern California, customers began to notice a different odor and taste to their tap water. Complaints began to mount, and the East Bay water municipality responded by letting customers know that due to the severe drought they needed to bring additional water in from the Sacramento River to supplement their current supply. The officials stated that the water brought in had a different makeup from the existing water.
In today's world where water is being imported and exported all over, it is possible to have the source water makeup change within hours. In some areas water is trucked in as a supplemental supply from hundreds of miles away where the pH, total alkalinity and calcium hardness can be drastically different from the local water. If this water isn't treated properly, it can cause balance issues in the pool. One prime recommendation for pool pros today would be to keep track of the source water by testing from the tap on a regular basis. This will help give a better understanding of how to treat the pool water.
How Fires Effect Pool Water
In 2015, Northern California experienced one the worst wildfire seasons in history. Three major fires were raging simultaneously. A total of 283,000 acres were burned. The ash from forest fires can be high in nutrients such as nitrates and phosphates. One of the main firefighting chemicals dropped from planes contains compounds of phosphate and so will contribute to phosphates in waterways over time. After one of the largest wildfires in San Diego in 2008, pool service professionals in the area saw a large spike in phosphate levels in pools. Testing for and treating pools for phosphates could be paramount immediately following forest fires. Phosphate removers can be very helpful in these situations.
What to Expect When It Goes From Dry to Wet
Every pool pro knows the importance of keeping pool water balanced. However what might not be known is the importance of adjusting water balance just before the first rain of the season. Acid rain is a phenomenon we have heard about as a result of pollution in our atmosphere. In the dry season there can be a buildup of nitrogen and sulfur compounds in the air. When the moisture from rain or fog combines with these compounds in the atmosphere, the result is nitric and sulfuric acid. When acid rain enters swimming pools it will have an immediate effect on lowering the pH. This explains why many times after the first heavy rain, pool pros report a drop in pH in many of their pools. One thing pool pros can do to prevent a drop in pH from acid rain is to make sure the total alkalinity is correct before the rain begins. Total alkalinity is the buffer to resist changes in the pH in water. Making sure that the total alkalinity is in the 80 to 120 ppm range can help to keep the pH from dropping when acid rain hits.
What's in Rain?
Unlike what we may think, rainwater is not pure. In fact, water is incapable of condensing into droplets without the presence of dust, smoke or other impurities in the atmosphere. A cloud of water droplets can only form in the presence of impurities. So those raindrops that you see splashing on the surface of the swimming pool are bringing with them organic and inorganic substances, bacteria and nitrogenous compounds of minerals and metals. It is very typical after a heavy rain for algae to become a problem in pools. This is because the rain itself can bring an increase in the levels of nitrates, which are a known food source for algae. Also, due to the impurities in rain water, chlorine demand can become much greater and sanitizer levels can be reduced to zero. It is vital after a heavy rain to test for nitrates. Super-chlorinate the pool often following heavy rains and use a good all -purpose algaecide.
The Hidden Dangers of Flood Water
There are several types of flooding that can occur. Flash floods are the result of a break in a levee or dam or heavy rains in mountain areas above a flood plain. This can be very destructive and cause contaminated water to rush quickly and overwhelm low-lying areas. In coastal regions storm surges and high tides can cause flooding. When Hurricane Sandy hit the coast of New Jersey, there were many pool service pros who reported finding live shrimp in their pools after the floodwaters receded. Floodwaters will contain mud, silt, organic materials and very possibly raw sewage that is loaded with bacteria. Whenever floodwaters enter a pool, it is best to drain the pool if possible. If this is not possible, then the pool should be super chlorinated to at least 20 ppm of chlorine at a pH of 7.5. The pool should be kept at 20 ppm for at least 15 hours to ensure that all pathogenic organisms have been inactivated. Also, the use of a natural polymer flocculent can help to clear materials out via the filter. The filter should be thoroughly cleaned once the water has cleared. You may also expect an influx of nitrates and phosphates from floodwaters particularly in agricultural areas or in areas of phosphate mining such as parts of Florida.
There is no denying that weather patterns are changing and in certain areas water itself has become a big challenge. Much of the southwestern United States has seen a drought unlike anything in more than 500 years. Groundwater levels have sunk to catastrophic levels and regulators have imposed strict conservation laws in reaction to this. The building, filling or draining of swimming pools has come under extreme scrutiny from many officials. Despite the fact that it has been proven that pools require less water to maintain than a backyard lawn, they still fall in the crosshairs of lawmakers and private citizens. Pool professionals need to be diligent during these times to ensure that the industry does not become falsely targeted as water-wasters. Having a plan in place on how to conserve and prevent waste of pool water is needed ahead of time. One of the largest water wasters mentioned previously will be evaporation, so if pool pros are diligent and do what they can to reduce the evaporative loss of pool water, that goes a long way in showing pro-conservation efforts. Solid covers can work, and if they are not an option, there are chemical liquid covers that can be applied to reduce water loss from evaporation. When the rains of El Nino begin to move in, it is important to be prepared by making sure all pools are properly balanced. Super-chlorinate after times of heavy rains or flooding. Test the pools for nitrates and phosphates, and be sure to use a good quality algaecide after the rains have past. We can't always predict the weather. But if we are ready for anything then we can prevent the water problems before they begin.
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