The weather is heating up, and Paradise Pool Service wants you to start pool season off right. One of the biggest complaints we hear from pool owners is all the guesswork involved in managing their water chemistry. Rest assured, you don’t have to be a chemist to maintain your pool water. This post will cover some basic water chemistry tips, so you can spend less time on maintenance and more time enjoying your backyard oasis.
What is Alkalinity and why do I need it?
To start pool season off right, alkalinity is the first chemical you want to adjust after you initially shock the pool at startup. Alkalinity works as a buffer. To put it simply, it helps your pool water to resist changes in pH. Without alkalinity, the pH can rapidly bounce between high and low with even small amounts of chemicals. This can cause a myriad of problems from cloudy water to equipment failure. If you’re testing your pool water yourself with a test kit, the ideal range for alkalinity is between 80-120ppm. It’s not uncommon to have to add alkalinity at the beginning of the pools season, but under normal conditions, it remains relatively stable throughout the season. The takeaway lesson here is do not make any changes to pH until you have tested and adjusted your total alkalinity.
Low alkalinity can result in water with a green tint if metals are present in the water. It can also cause corrosion of your pool walls and surfaces. To increase alkalinity, you would add sodium bicarbonate.
High alkalinity can cause pH lock, making the pH level very hard to change. This most commonly causes cloudy water. Total alkalinity can be lowered by adding either muriatic acid or sodium bisulfate.
The Importance of Controlling pH
You may remember from high school chemistry that pH is a measure of the hydrogen ion concentration in water and ranges on a scale from 0 to 14. The closer to 0, the more acidic the water is, and the closer to 14 the more basic. As a pool owner, all you really need to know is that the recommended pH of pool water is slightly alkaline (7.2 – 7.6). Control of pH is extremely important for the comfort of swimmers, proper disinfection, and the protection of pool structures and equipment. When pH is out of balance, chlorine does not properly disinfect the water. pH should be tested and adjusted on a weekly basis for proper water chemistry.
Low pH can cause corrosion of pool equipment and surfaces, as well as eye and skin irritation in swimmers. In order to correct low pH, a base must be added to the pool. This is usually in the form of sodium carbonate (soda ash).
High pH most frequently causes chlorine inefficiency. This can be very dangerous to swimmers because the pool water is not properly disinfected. Swimmers are subjected to health hazards including eye and skin irritation, as well as rashes and bacterial infections. High pH is also a common cause for cloudy water and clogged filters and heaters. This is because water with a high pH causes a scaling effect.
What does Chlorine do?
Chlorine is a disinfectant that inactivates or kills the vast majority of microorganisms (bacteria, viruses, fungi, and protozoan) in the pool water. In addition, chlorine is effective at killing algae in pool water. Free chlorine refers to the amount of chlorine in the water that is available to disinfect. It is important that pool owners keep free chlorine in the recommended range of 1-4ppm. Chlorine levels should be tested and chlorine should be added to the pool on a weekly basis or after a heavy swim load.
Do I really need Calcium Hardness?
The short answer is yes, especially if you have a plaster or concrete pool. The reason for this is that calcium is naturally present in water due to the leaching process that occurs in nature. If the calcium level in your pool water is too low, the pool water will become increasingly aggressive, leaching calcium out of the plaster. This causes corrosion and breakdown of plaster and concrete pool surfaces. High calcium can also be a problem because it causes scaling of pool surfaces and equipment.
High calcium is difficult to treat and most commonly results in partial draining and filling of the body of water.
Low calcium can be corrected by adding calcium carbonate to the pool. This is most commonly available in the form of calcium carbonate flakes. Pre-dissolving the calcium in a bucket of water and adding it to the deepest area of the pool is recommended. A pro tip is to always add calcium to water, do not add water to calcium. Use a non-metal object, such as a wooden stick to mix, as the mixture becomes hot. Once calcium is added to the pool, under normal conditions, the level will generally remain relatively stable throughout the season.
What is Cyanuric Acid?
Cyanuric acid helps to stabilize chlorine and protect the free chlorine compounds from the effects of UV light. Did you know that half of the chlorine in water can be destroyed by sunlight in less than 1 hour? As a result, free chlorine levels drop, and the water is no longer properly disinfected. By adding cyanuric acid (also called stabilizer or UV shield) free chlorine residuals will remain in the pool 3 to 10 times longer. The most recent recommendation for cyanuric acid levels is 30-50 ppm or 20ppm in pools using salt chlorine generation. Cyanuric acid is a chemical that when added at the beginning of the season, will remain in the water at a relatively stable level. Too much cyanuric acid is very difficult to remove, and often requires partial drain and refill of the body of water.
We hope this post has been helpful in answering some of the most common water chemistry questions. By following the tips above, you can ensure your water stays clean, clear, and properly sanitized. Wishing you a stress-free pool startup and a happy, healthy swim season!