Water Balance, A Year Round Science

Maintaining your swimming pool is more of a science than most realize. Chemistry in your pool is in constant motion. From environment, weather and swimmers to debris, temperature and waste, the chemistry of a pool is ever evolving. The filtration equipment helps to reduce contaminates and make swimming more enjoyable, but does not keep the chemistry balanced.  Balanced water has the correct levels of pH, total alkalinity and calcium hardness as well as sanitizer levels. Properly balanced water is described as neither being corrosive or scaling.

Water will continue to dissolve minerals until it is completely saturated and cannot hold any more. When water is considerably under saturated it is corrosive. Just as it sounds, corrosive water can corrode your pool and equipment. Over saturated water can no longer hold mineral and creates a scaling condition. This can cause mineral build up in your pool, plumbing structure and filtration equipment. Mineral build up can lead to slower or blocked water flow within the filtration system and burn up your pool motor. As part of our service to you we test your water on each visit and adjust as necessary.

pH is a measure of how acidic or basic the water is.  pH is a logarithmic scale from 0-14, with 7 being neutral.  Below 7 is acidic, while levels above 7 are alkaline.  Everything in your pool has a pH value.  Ever heard of acid rain?  This is rainfall with a very low pH.  The human eye has a pH value of 7.35.  This is how we measure the proper pH for your pool.  To have pH in balance we adjust the water with additions of pH increasers (bases) or pH de-creasers (acids) to attain the range of 7.2 – 7.8.  If your testing (recommended daily) of the water shows a pH value below 7.2 the water is in a corrosive (acidic) condition and you will need to add a base to bring the pH into a more basic range to prevent corrosion.  On the other hand, if the pH is above 7.8, we are in a scaling (basic) condition and must add an acid to bring down the pH to prevent the formation of scale.

A close cousin of pH, the level of alkalinity in the water is a measurement of all carbonates, bicarbonates, hydroxides, and other alkaline found in the pool water.  pH is alkaline dependent; that is, alkalinity is defined as the ability of the water to resist changes in pH.  Also known as the buffering capacity of the water, alkalinity keeps the pH from “bouncing” all over the place.  Low alkalinity is raised by the addition of a base (similar to pH); sodium bicarbonate is commonly used.  High levels of alkalinity are lowered by the addition of an acid (similar to pH).

When we speak of scale, we are talking about calcium carbonate, which has come out of solution and deposited itself on surfaces.  It is a combination of carbonate ions, a part of total alkalinity and calcium, and a part of the Calcium Hardness level.  The test for Calcium Hardness is a measure of how “hard” or “soft” the water is testing.  “Hard” water can have high levels of calcium and magnesium.  If these levels are too high the water becomes saturated and will throw off excess particles out of solution, which then seeks to deposit themselves on almost any surface inside the pool.  This is calcium carbonate scale; a “white-ish,” crystallized rough spot. If the levels are too low, the water is under-saturated.  If under-saturated, the water will become aggressive as it attempts to obtain the calcium it needs.  Such “soft-water” will actually corrode surfaces inside the pool which contain calcium and other minerals to maintain its hardness demand. Keep in mind that calcium is a natural substance and will build up even with a perfectly balanced pool everyday. Keeping your water balanced helps to reduce some build-up

As you can see, it is an amazing science to maintain your swimming pool, and this is only one element of your pool that we must monitor. The dance we do on a weekly basis with chemistry must be precise. As we transition into fall the balances of your water can massively fluctuate even more with falling leaves and high debris.  So next time you jump in you can be confident that your service provider is taking care of the science so you can sit back and relax.