Calculating Chemical Additions

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Suggested Residential Pool or Spa Chemistry Ranges
(Scroll down the page for help with dosages.)

Varies with spa use.

*  Cyanuric Acid levels over 50 PPM are not likely to provide any additional benefit or protection and will reduce the effectiveness of chlorine, as the levels rise above 50 PPM.  Coverted spas do not require this chemical.
**  Cyanuric Acid levels over 50 PPM require increasingly higher amounts of free chlorine, to provide the same degree of sanitation, as when the CYA levels are closer to 50 PPM.  For best results lower the level to under 50 PPM.  The use of stabilized chlorine will cause the cyanuric acid level to rise, as product is added.  To avoid this issue, stop all use of stabilized chlorine and switch to a salt chlorine generator or alternative form of chlorine.

Raising or lowering the pH will, will usually, move the Total Alkalinity in the same direction. It is not always practical to get both parameters within range. pH is always more important! If the pH is in range and the TA is higher, it may not present problems, so long as the water is clear and there are no signs of scaling. The higher the TA, the more stable the pH becomes, and the more chemicals will be required to move it, in any direction. A high TA and an acceptable pH is not a problem, so long as the water is clear and there are no signs of scale formation. The lower the TA, the less stable the pH becomes, and the easier it moves up or down. Having the right tester will make your test results more reliable and make maintaining the water chemistry easier and less expensive. These amounts are just guides. Your pool or spas could require more. or less, based on the overall sanitizing method. Remember, you can add more - you can't take out.

The above dosages are just a guide and your pool could require more or less. Pools with higher total alkalinities and TDS could require more. Add slowly in increments, in front of a moving return flow. Remember you can always add more - you can't take out! Go to the Chemical Safety Practices page, for more about proper procedures and handling. Larger or smaller pools or spas, use proportionate amounts.

The above dosages are just a guide and your pool could require more or less. Pools with higher total alkalinities and TDS could require more. Add slowly in increments, in front of a moving return flow. Always add the acid to the pool water. Go to the Chemical Safety Practices page, for more about proper procedures and handling.  Larger or smaller pools or spas, use proportionate amounts.

Raising or lowering the Total Alkalinity will move the pH in the same direction. It is not always practical to get both parameters within range. pH is always more important! Low TA makes the pH less stable. High TA makes the pH more stable, but can lead to scaling issues, if the calcium hardness is over 400 PPM. If the calcium hardness is too high, a TA closer to 80 PPM should be of benefit. If the TA is high and the pH is within range and the water is clear, without any signs of scaling, there is no compelling reason to have to lower the TA. Attempting to do so, may prove futile. To get a truer TA reading, you should subtract 30% of the Cyanuric Acid test reading, from the TA reading. Having the right tester will make your test results more reliable and make maintaining the water chemistry easier and less expensive. These amounts are just guides. Your pool or spas could require more. or less, based on the overall sanitizing method Remember, you can add more - you can't take out.

The above dosages are just a guide and your pool could require more or less. Pools with higher total alkalinities and TDS could require more. Add slowly in increments, in front of a moving return flow. Always add the acid to the pool water. Go to the Chemical Safety Practices page, for more about proper procedures and handling.  Larger or smaller pools or spas, use proportionate amounts.

The above dosages are just a guide and your pool could require more or less. Add slowly in increments, in front of a moving return flow. To obtain a truer TA reading, subtract 30% of the Cyanuric Acid reading from the TA reading. Remember you can always add more - you can't take out! Go to the Chemical Safety Practices page, for more about proper procedures and handling.  Larger or smaller pools or spas, use proportionate amounts. Your pool or spa could require more. or less, based on the overall sanitizing method.

Having the right tester will make your test results more reliable and make maintaining the water chemistry easier and less expensive. High levels of calcium hardness can lead to cloudy water, scaling, heater and filter issues. Low calcium hardness, in gunite pools can lead to etching of the surface and problems with the appearance of the finish. Calcium may be present in source water to varying extents. The use of calcium hypochlorite, as a chlorine source or shock treatment, will increase the hardness of the pool water, over time. These amounts are just guides. Your pool could require more or less, depending on the accuracy of the test. Remember, you can add more - you can't take out.

The above dosages are just a guide and your pool could require more or less. Add slowly in increments, in front of a moving return flow or by broadcasting across the surface. Vinyl and Fiberglass pools can do well with lower levels, as their walls are not made of masonry materials. Gunite pools should maintain a higher level, to help protect the walls and minimize the tendency of the pH to rise, as calcium dissolves from the plastered surface. High pH and/or TA make cloudy water more likely, as this chemical is added.  Larger or smaller pools, use proportionate amounts. Lowering Calcium Hardness can be done, by replacing some of the water with softer water. Adding 1 pound of Tri Sodium Phosphate (TSP), per 10,000 gallons of pool water, will drop the calcium harness by 11 PPM. However, this will cause cloudiness, a major amount of cleaning of the pool and filter and the possibility that any lingering phosphates will promote algae growth. Calcium sequestering agent are another choice for dealing with high calcium levels. Go to the Chemical Safety Practices page, for more about proper procedures and handling.  Larger or smaller pools or spas, use proportionate amounts. Your pool or spa could require more. or less, based on the overall sanitizing method.

Having the right tester will make your test results more reliable and make maintaining the water chemistry easier and less expensive. Cyanuric acid is only used in chlorine-maintained outdoor pool and helps to make the chlorine lake longer, by protecting it from the Sun's UV rays. In northern areas a range of 20-40 PPM is recommended.  At higher levels, cyanuric acid makes the chlorine less effective and forces to pool owner to maintain a higher free chlorine level. The only way to lower a high level is to replace some of the water, preferably in increments, to avoid damage to the pool. These amounts are just guides. Your pool or spa could require more or less, depending on the accuracy of the test. Remember, you can add more - you can't take out. THIS CHEMICAL IS NOT REQUIRED IN SPAS THAT ARE COVERED, MOST OF THE TIME.

The above dosages are just a guide and your pool should require these amounts, providing the testing was reasonably accurate. Add slowly in increments, in front of a moving return flow or by broadcasting across the surface. Adding it very slowly, to the skimmer, is another way to add this slowly dissolving chemical. Pools that use Trichlor or Dichlor will find that their cyanuric acid levels will rise over time. If trichlor is used as the primary sanitizer, dichlor as a shock should be avoided, as it will only speed up the rise of the cyanuric acid level. Water replacement is the only means of lowering a high level. Go to the Chemical Safety Practices page, for more about proper procedures and handling.  Larger or smaller pools or spas, use proportionate amounts.  To avoid a rising cyanuric acid  issue, stop all use of stabilized chlorine and switch to a salt chlorine generator or alternative form of chlorine.  THIS CHEMICAL IS NOT REQUIRED IN SPAS THAT ARE COVERED, MOST OF THE TIME.

Having the right tester will make your test results more reliable and make maintaining the water chemistry easier and less expensive. Which product to use is a matter of what is best for your water chemistry, as well as cost-effectiveness and convenience factors. Liquid chlorine is cost effective and adds no problematic byproducts, but is not necessarily convenient. Calcium hypochlorite is cost effective, but can add unwanted calcium hardness. Dichlor is convenient and easy to use, but tends to raise the cyanuric acid level. Lithium Hypochlorite is convenient, but less cost effective. These amounts are just guides. Your pool or spa could require more or less, depending on the state of the water quality. Remember, you can add more - you can't take out.

Superchlorination is used to help destroy algae, restore water quality and to eliminate the odorous and irritating forms of chlorine. Boosting the free chlorine to 10 PPM, will destroy 1.0 PPM of combined chlorine. Combined chlorine is the difference between the Total Chlorine reading and the Free Chlorine reading. Test values under 0.3 PPM are indicative of good chlorine management. Reading between 0.3 and 1.0 PPM, indicate that more attention may need to be directed to the chlorine application rate. Readings over 1.0 PPM are likely to result in eye irritation and odorous conditions. Go to the Chemical Safety Practices page, for more about proper procedures and handling.  Larger or smaller pools, use proportionate amounts. Your pool or spa could require more. or less, based on the overall sanitizing method.

Having the right Salt and TDS Tester will make your test results more reliable and make maintaining the water chemistry easier and less expensive. High TDS could lead to water quality issues and might be treated simply by replacing some of the water. With a salt chlorine generator, it is important to monitor the salt level, to get optimum performance and help extend the life of the salt cell. Too low a salt level could make it difficult to maintain a proper free chlorine level and could shorten the life of the salt cell. Too much salt will shorten the life of the salt cell, make pH control more challenging and add to the possibility of corrosion and clarity issues. These amounts are just guides. Your pool or spa could require more or less, depending on the accuracy of the test. Remember, you can add more - you can't take out.

Total Dissolved Solids (TDS) has to be separated into two categories. TDS that results from naturally occurring mineral salts, build up of chemical residues and waste from bathers. What is present in the source water may not be controllable and pool or spa usage will add to the TDS level. As this level rises to 2000-3000 PPM, the possibility exists that it will affect water clarity, scaling and sanitizer performance. Depending on the nature of the available replacement water, it may be difficult to drastically lower the level. High TDS that results, from the addition of the required amount of salt when a salt chlorine generator is used, presents a different problem. 2500-4000 PPM of salt may have to be added, depending on the manufacturer's recommendation, and does not present the same issues, unless the water was high in TDS before the salt was added. If that is the case, clarity, scaling and corrosion issues could present themselves.  Addition of sequestering agents could help minimize problems and help keep the salt cell free of scale. Go to the Chemical Safety Practices page, for more about proper procedures and handling.