Understanding water chemistry is an essential part of caring for and maintaining your swimming pool or spa. Knowing how different factors such as pH, Total Alkalinity and Calcium Hardness affect your water and equipment will save you a lot of time, money, and frustration. Knowing more will leave you better prepared to get the water in your pool or spa properly balanced the first time, saving you money by adding just what is needed at the right time, instead of heavy doses to fix any previous oversight. Now let's see what are the MOST IMPORTANT factors controlling the water balance in your pool or spa:

How pH Affects Water Chemistry

   Simply stated, pH is the measure of the relative acid or base of the water. The ideal level for swimming pools and spas is between 7.2 and 7.8. It is recommended to be tested daily, and can be tested for with any water testing kit. A pH level above 7.8 will lead to cloudy water, staining, scale deposits, filtration problems, and reduced chlorine efficiency. This means you can save money on chlorine by making sure the water in your pool or spa has pH in the appropriate range. If pH falls below 7.2, it could lead to corrosion of metallic pipes, etched plaster, rapid loss of chlorine residual, and possible irritation to swimmers. To maintain an ideal pH level in the water, use a pH Increaser (pH+) when the pH drops below 7.2 and a pH Reducer (pH-) when the pH rises above 7.8.

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Total Alkalinity - What It Means To Pool and Spa Water

   Total Alkalinity is the measure of the water's ability to resist change in pH. Alkalinity does not have to be tested for as often as pH. Good Total Alkalinity will make it much easier to maintain good pH. The appropriate range for Total Alkalinity in pool and spa water is between 75 and 120 mg/l. High Total Alkalinity (above 120 mg/l) will allow your pH to slowly creep up and resist efforts to change. Low Total Alkalinity (below 75 mg/l) allows your pH to "bounce" from one extreme to the other, making it very difficult to keep your pH in the appropriate range. Ideal Total Alkalinity (between 75 and 120 mg/l) can be achieved by adding Alkalinity Increaser if the Total Alkalinity is below 75 mg/l and pH Reducer (pH-) if Total Alkalinity is above 120 mg/l. Alkalinity tests should be conducted once a week or as needed.

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Calcium Hardness and How It Affects Water Balance

   Calcium Hardness is the amount of dissolved calcium in the water. The ideal amount of dissolved calcium is between 200 and 400 mg/l. Calcium Hardness above 500 mg/l (high Calcium Hardness) can cause calcium to precipitate from the water causing cloudy conditions and scale deposits. Low Calcium Hardness (below 100 mg/l) can lead to corrosion. A low calcium hardness level can be corrected by adding Water Hardness Increaser. If it is required to reduce the level of calcium hardness the only way is to dump some of the water and top up with fresh, containing lower natural hardness. Calcium hardness tests should be performed when the pool or spa is filled or once every two to three months.

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Shocking and TDS

   Shocking with chlorine or non-chlorine chemicals will burn out the chloramines in the water that may have formed. Also known as super-chlorinating, this practice will fight water problems like cloudy water, skin and eye irritation, and foul odors. These symptoms are usually a result of the presence of those dreaded chloramines. Shocking should be done at least once a week.

   TDS, or total dissolved solids is important for one reason. The higher TDS becomes the less effective your addition of chemicals will be. It should be monitored by comparison between the pool/spa water and the mains feed water. TDS should ideally not be allowed to rise more than 1000 mg/l above the feed water, up to a maximum of 3000 mg/l. Telltale signs of high TDS are salty-tasting water or water with dull appearance. If you think that your TDS may be too high, contact a professional service technician to have it tested. Should it become necessary to reduce the TDS level, this is carried out by replacing some of the water in with fresh water. In some pools/spas a satisfactory TDS level can be maintained by regular backwashing of the filters.

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Sanitizing the Water in your pool or spa

   Making sure all the preceding factors of pool water balance are within their appropriate levels will allow you to sanitize the water in your pool or spa with fewer headaches, and amount of chlorine, than ever before! Disinfecting is an essential element of any water treatment program. Stabilized Chlorine is designed to disinfect your water by releasing "free chlorine" into the water to control germs and other microorganisms, algae and organic matter. Because water conditions change rapidly, it is very important to test the water every day for chlorine residual. The free available chlorine reading should be between 1.5 - 3 mg/l.

Protecting Your Chlorine From Sunlight

   At the start of each season it may be necessary to add Stabilizer. Sunlight can rapidly destroy chlorine residual in outdoor pools and spas unless the water is "stabilized". The Stabilizer will shield your chlorine from rapid destruction by sunlight. In effect it will make the chlorine you buy last longer, saving you money in the long run.


   With this basic information on water chemistry you can fully understand the chemical implications of maintaining properly balanced water. We recommend taking the time to understand these factors as they will save you both time and money, leaving you more of both to spend on enjoying, not maintaining, the water in your swimming pool or spa.

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Recommended Ranges of Water Chemistry:

   pH -7.2 - 7.8
   Total Alkalinity - 75 - 120 mg/l
   Calcium Hardness - 200 - 400 mg/l
   Free Available Chlorine - 1.5 - 3 mg/l

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Winterizing your pool

   Winterizing the pool requires knowledge about the chemicals processes that take place in the pool as well as the water quality indicators. If you are unsure about your capabilities to handle the task, consult a professional.

   fter the actve use of the pool is over, it is necessary to continue the water treatment program until the temperature drops below 15 degrees Celsius. At this point the pool should be winterized. It is neccessary to perform all of the following tasks:

  1. Brush the pool walls. The pool bottom should be thoroughly cleaned with a vacuum cleaner. Before doing this you can use water clarifier (flocculant) to join the smallest particles into bigger ones so they can be removed from the water. The filter valve can be set to waste. Dosing level of the clarifier is 100 ml per 10 cub. m of water.
  2. Drain the pool water to a level just under the bottom of the skimmers as a prevention against freezing, close the skimmers' valve, and leave the drain valve open. Never drain the pool completely. Put plastic bottles filled with little sand or water (the bottles should still be able to float on the surface). There should be enough bottles to compensate for the expanding ice. In order to prevent the bottles from ending in one corner, it is a good idea to tether them around the pool.
  3. Adjust the total alkalinity within the range 80-120 mg/l (ppm):
    - To reduce the total alkalinity with 10 mg/l (ppm), dillute 180 g of the chemical рН- for every 10 cub. m of pool water in a bucket (the ratio water:рН- should not be stronger tnah 8:1) and pour it in the deep end of the pool with the pump not running. Don't add more than 300 g of the chemical per 10 cub. m of water in every single treatment.
    - To increase the total alkalinity with 10 mg/l (ppm) dillute 160 g of the chemical Total alkalinity booster for every 10 cub. m of pool water in a bucket and pour it along the pool walls. Don't add more than 300 g of the chemical per 10 cub. m of water in every single treatment.
  4. Adjust the pH within the range 7,2-7,6:
    - To reduce the pH with 0,1 dillute 80 g of the chemical pH- for every 10 cub. m of pool water in a bucket and pour it along the pool walls. Don't add more than 300 g of the chemical per 10 cub. m of water in every single treatment.
    - To increase the pH with 0,1 dillute 80 g of the chemical pH+ for every 10 cub. m of pool water in a bucket and pour it along the pool walls. Don't add more than 300 g of the chemical per 10 cub. m of water in every single treatment.
  5. Perform a shock treatment of the pool with 200 g of Dichlor or Trichlor for every 10 cub. m of pool water. The free chlorine level should be in the range 6 - 10 mg/l (ppm).
  6. Pour 300 ml Algicide for every 10 cub. m of pool water evenly over the water surface. If possible, pour additional 150 ml Algicide for every 10 cub. m of water after three months.
  7. Turn on the filtration for 6 - 8 hours to circulate the chemicals.
  8. The next day, after backwashing the sand filter, pour solution of the chemical Filter Clean in the filter. The filtration shoul be turned off for 8-10 hours. After that, it is necessary to perform a backwashing cycle of the sand filer.
  9. After the water has circulated long enough for the chemicals to mix thoroughly, the pump can be turned off and drain the water from the filter, the heater, and the pump. They all should have drain plugs at the bottom.
  10. If you have a winter cover, it is a good idea to install it at this point to prevent leaves and other debris from entering the pool.

   In early spring - late February/March, as the days get longer and the weather gets a bit warmer keep and eye on your water. As the long life algicide starts to wear off you may need to run the pump to circulate a bit of chlorine or algicide in the pool to keep the algae at bay until you are ready for the spring open up.

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