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Target LSI is between -0.3 and +0.3
LSI (Langelier Saturation Index) is all about calcium carbonate saturation, which determines if your water is aggressive/corrosive (low LSI), balanced, or scale-forming (high LSI).
LSI is calculated on 6 factors:
· Water Temperature
· Calcium Hardness
· Alkalinity
· Cyanuric Acid
· pH
· TDS
Low LSI can cause etching and corrosion.
High LSI can cause cloudy water and scaling.
Warm water - Bacteria thrives in warm water conditions due to warmer water allowing microorganisms to reproduce at faster rates. For this reason, the chlorine demand goes up.
Cold water – Lowers the LSI and makes the water more aggressive, or corrosive. Chlorine lasts much longer.
Target calcium hardness is above 300
Calcium hardness is the amount of dissolved calcium in the water.
Low calcium hardness can cause etching.
High calcium hardness can cause calcium deposits on pool surfaces and equipment.
Target alkalinity is 120-150 with the exception of salt pools.
Target alkalinity for salt pools will depend on the LSI.
Alkalinity is the buffer for a pool’s pH.
Low total alkalinity (below 120) can cause pH to bounce and fluctuate. It can also cause corrosion and staining.
High total alkalinity (above 150) can cause pH to bounce and fluctuate. It can also cause cloudy water and scaling.
Target CYA is 30-50ppm
When CYA rises to 150+, we need to drain the pool.
CYA is also called stabilizer - it protects chlorine from evaporating from the pool water. This chemical is the culprit for most pools needing to be drained every 2 years. There is no way of getting CYA out of the water once it is put in, other than RO (reverse osmosis), or draining.
When the pool is first filled with water, CYA is added as one of the startup chemicals. This is added to guarantee the longevity of chlorine in the water. However, other chemicals also have CYA in them. When these other chemicals are introduced to the water, over time the water becomes highly saturated with CYA; requiring it to be drained. The other chemicals that have CYA in them are:
Low CYA can cause chlorine to evaporate quickly, resulting in algae and other issues.
High CYA can cause chlorine to evaporate quickly, resulting in algae and other issues.
Target pH is 7.5 with the exception of salt pools.
Target pH for salt pools will depend on the LSI.
pH is measured on a scale from 0 to 14. 0-7 is considered acidic. 7 is neutral. 7-14 is considered basic.
Low pH (below 7.2) can cause etching in plaster, metals, and equipment.
High pH (above 7.8) can cause scaling or cloudy water.
pH that is too low or too high can cause chlorine to be ineffective.
Target TDS is below 2000 with the exception of salt pools.
TDS is the sum of substances dissolved in pool water. Everything added to the water increases the TDS level, including swimming in it. When the TDS is in range, chemicals can be added to the water, where they dissolve into the water and balance chemistry. Once the TDS is too high, chemicals added to the water no longer dissolve and balance chemistry. The water has reached its limit and cannot absorb more chemicals.
Low TDS can cause chemistry to be balanced.
High TDS can cause improper chemical balance, leading to algae, etching, scaling, or the pool being drained.
Target FC is between 3 and 6 ppm
FC should be 7.5% of CYA
Chlorine breaks down bacteria and sanitizes pool water. We use granular chlorine, chlorine tablets, and liquid chlorine. They all play a part and are used at different times for different reasons.
Free chlorine is the chlorinated water that has not interacted with any contaminants and is ready to sanitize future contaminants. It is the amount of chlorine that is still available to sanitize pool water.
Free chlorine is effective at just 1ppm, however, we elevate this to ensure quality, safe, crystal-clear water.
Low free chlorine (below 3) can cause cloudy water and algae to form, depending on outside temperature and other factors.
High free chlorine (above 6) can cause bather (the swimmer) irritation, and in extreme cases, lung irritation, skin and eye damage, and provoke asthma. High levels can cause the pH to drop, making the water more acidic and more prone to etching.
Combined chlorine is the by-product of free chlorine oxidizing contaminants, such as nitrogen and ammonia. This is the "used up" chlorine.
Bromine is like chlorine; however, it performs better in hot water. For this reason, bromine is commonly used for stand-alone spas.
Bromine and chlorine should never be mixed as the chemicals have dangerous interactions.
Target phosphates is 0
Phosphates are organic materials left behind from leaves, fertilizer, shampoo, etc. They are the food source for algae. Thus, if phosphates can be found in the water, algae can be too.
Low phosphates can cause clear, algae free water.
High phosphates can cause cloudiness and algae.
Target salt level is 3500 (mostly)
Some salt systems call for different salt levels. It's best to verify with the manual.
Salt is just standard NaCl, sodium chloride. It is made up of two elements, sodium and chlorine. In pool water, it breaks down into sodium ions and chlorine ions.
Low salt can cause the salt cell to not product enough chlorine.
High salt can cause corrosion in extreme cases.