Frank and Jacque talk about water balance and water chemistry. Why is the LSI Langlier Saturation Index important in your pool, and how do you manage it?
00:00-04:50 It must be Halloween found a bat in a skimmer; the plaster finisher didn’t use stainless steel set screws when reinstalling the pool light fixture
04:51 Facebook question asking if they should be concerned about pH being high in their pool. The answer is a little high or a little low is ok as long as the LSI is in a good range. Then people asked what LSI is.
05:40 Anyone managing a swimming pool should understand LSI, Langlier Saturation Index. LSI is water balance. Water seeks a saturation equilibrium. There. There are a few things that determine what that equilibrium is. Water temperature, pH, alkalinity, calcium hardness, total dissolved solids, and, to a degree, cya, borates, and a few other factors. All of these go into a formula that allows you to calculate if the water is aggressive, meaning it wants to dissolve anything it can to become saturated, which can etch pool surfaces or weaken and damage equipment, or scaling, which is the water has too much stuff dissolved in it, and it wants to push the dissolved materials out of solution, or precipitate, which can cause scaling or staining.
06:45 Water chemistry, balance, and sanitizers are part of pool maintenance. Chemistry alone will not keep your pool water looking good and safe. You still need good filtration, circulation, removal of debris, and brushing.
17:45 To achieve proper chemistry, you must properly test your water, and do not dose a chemical without testing it first. Measure doses; do not guess amounts. It is recommended that most chemicals, acids, shocks, etc.. be diluted in a bucket of water when adding it to the pool. Always add chemicals to water, not water to chemicals. Keep records for test results, chemicals added, filter pressure, and water condition. There are apps available that can make calculating LSI easy. We like the Orenda app.
Water temperature changes the water balance. As temperatures increase, the LSI increases, and as they decrease, the LSI decreases. So the average pool LSI will change quite a bit during the year due to water temperature. Typically scale will first develop in areas where the water temperature is slightly warmer.
Calcium, in most pools, will naturally increase over time. The only way to decrease calcium in water is to remove or dilute the water, use reverse osmosis, or push it out of the solution by violating the LSI and turning it into the scale in the pool.
total dissolved solids are everything that has been dissolved into the water
cya, and borates affect LSI through their effect on alkalinity test results
Alkalinity is the total of carbonates, bicarbonates, hydroxides, and a few other things to a lesser degree. It is called the buffering capacity of water. It resists the effect of acids and bases on the LSI. Too low or too high alkalinity makes it difficult to control pH. Alkalinity should be tested weekly and managed pretty closely.
Ph has the biggest impact on LSI, and it typically is the parameter in LSI that changes the most. pH can change hourly in a pool. It is extremely important that you test pH regularly and adjust as needed.
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Do you have a pool question for Frank? You can email him at [email protected]. He just might read and answer your question on air!