Water Chemistry 101

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It is very crucial to know that a crystal clear pool does not mean a correctly balanced pool. Clear pool water may only mean chlorine is most likely present and the filter is working properly. Weekly swimming pool maintenance is important because water is very demanding with what it wants, and if it is not given the proper ranges it will pull it from the next closest thing, the plaster on your gunite pool. I will briefly touch base on all the important chemistry factors that ties into proper pool care for the safety of your filtration equipment, plaster, and most importantly your swimmers!

Yes, chlorine is a very well known ingredient in a swimming pool, whether you are using tablets or a salt generator to generate chlorine it is read on a scale from 0.5ppm to 10+ppm. Have you ever been in a pool where your eyes burned and your skin has felt super dry when you got out? The prefect range of proper chlorine levels is where your pool will be crystal clear and you wont even know chlorine is present in the water! 

1ppm-3ppm*

*Parts per million

The range of PH levels read from 0 to 14. A low PH is characterized by acidic and a high PH is alkaline. When it come to swimming pools, we aim to keep the range as neutral as possible, a PH that is too acidic or alkaline can cause damage to your equipment, plaster, and cause irritation to swimmers. Fun fact, The human blood PH level is naturally neutral around 7.365*, and we adjust for that neutral range.

7.2-7.4 

*(https://alywillow.com/pages/understanding-ph-levels)

This is a measurement of the water's ability to resist change in pH. Commonly preferred to as a PH buffer. In order to maintain a more stable PH level it is important to calculate and adjust the total alkalinity for a range of 80ppm-120ppm.

The right amount of calcium in you water protects your equipment and plaster. Keeping you calcium levels from falling too low is a key factor to protecting your plaster from etching, rough surfaces, dissolving of grout and cloudy water. If we go the other way, a calcium level that is too high can cause pitting of your concrete pool deck, clogged filters and reduced circulation through piping along with heater inefficiency. An ideal calcium hardness range we aim for is between 200ppm-400ppm.

Cyanuric acid is kind of like sunscreen for chlorine, this molecule can get a little technical with the terms but in short, it attaches to the present chlorine in the water and allows the chlorine to let go of the cyanuric acid when it has something to oxidize or kill. Without the proper amount of cyanuric acid your available chlorine levels in the water are going to be a lot less efficient and burn off, causing you to run through more chlorine tablets than needed or issues with your salt cell generator not being able to keep up with the demands.  The efficient ranges for a chlorine tablet/granular pool is 20ppm50ppm or If a salt generator is present we raise it to 70-80ppm.

This is one of the biggest foods for algae growth. There are three major ways phosphates enter your pool, through Chemicals, organically such as fertilizers, or the tap water you use to top your pool off every once in awhile. Due to high phosphate levels in your pool, your free chlorine is then occupied killing algae, less is available to form a sanitizer residual. High phosphate loads, when left untreated, will generally result in higher chlorine demands. A healthy phosphate level to be maintained is less than 100ppb*

*Parts per billion

Only adjusted for in swimming pools that have salt generators installed. A pool with a salt water generator transfers electricity through a salt cell generator but it is very crucial to have the proper amounts of salt present in the water for it to efficiently generate chlorine. An efficient range of salt levels are 3,400ppm-3,600ppm.

Total dissolved solids (TDS) consist of inorganic salts (ie. principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides, and sulfates) and some small amounts of organic matter that are dissolved in water. A recommended TDS level is 1,500ppm or lower. 

Well first off, you made it down this far so I am very proud of you for educating yourself, I know chemistry can get a little overwhelming! This is the last but TOTAL piece of the water chemistry puzzle that ties everything together. The LSI has a healthy range from -0.30 corrosive (negative LSI) up to +0.30 scale-forming (positive LSI). So in theory a 0.00 on the LSI scale is perfect equilibrium. If water chemistry is out of balance, it will naturally try to find its own balance and equilibrium, because it wants to be at 0.00 on the LSI scale. If too far beyond this range is where problems can occur for your pool ie. etching in corrosive water or scaling. For instance, if there is not enough calcium, water will dissolve and extract it from the most readily available source. That means the cement in the plaster or pebble finish. To calculate the precise LSI it involves seven factors, below:

• Water Temperature
• PH
• Calcium
• Alkalinity
• Cyanuric Acid
• Salt
• TDS

With the proper balancing of the water, a healthy LSI between -0.30 and +0.30 can be achieved, protecting you beautiful investment for many years.