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A Guide to Proper Pool Water Chemistry

Categories: How To Guides, Chemicals, Maintenance & Upkeep
Summer is the perfect season for pool owners to enjoy their backyard paradise. With warm sunshine, delicious barbecues, and inviting crystal-clear water, it's no wonder that swimming is a favorite pastime.
However, many pool owners feel daunted by the prospect of managing their water chemistry and equipment. As a result, they often rely on expensive pool maintenance services to keep their pool in good condition. However, you don’t need to spend your hard-earned money paying a pool company to do regular testing, and you definitely don’t need to go out and buy a copy of “pool chemicals for dummies” to get the job done right.
By taking a few minutes to learn which few basic chemicals you need to monitor and how to monitor them, you can keep your pool water clean, safe, and inviting all summer long without calling in any reinforcements.
Why Proper Pool Chemistry Matters
Anyone who’s had trouble keeping their eyes open while swimming underwater has experienced firsthand the perils of poor water chemistry. But imbalanced pool chemistry can lead to more than just irritation. It can also be a breeding ground for bacteria and create problems like staining, corrosion, and degradation of metals on your pool equipment and accessories.
By keeping your pool’s chemical levels in check, you’ll not only help keep your water clean and clear, but you’ll also help prolong the health of your pool, reduce the opportunity for bacteria and algae to grow, and ensure your family and friends enjoy your pool without stinging eyes or irritated skin.
How Often Should You Test Your Pool Water?
Pool professionals suggest testing pool water a couple of times per week in the heart of swim season when the harshness of sunlight and body oils and fluids can combine to create problems. It’s easy to forget to be so vigilant, but water problems that are diagnosed early generally require much less corrective action.
Pool Chemistry 101: The Basics
Water chemistry is relatively simple to maintain under normal use and manageable weather conditions. Experts advise there are just a handful of basic chemicals to keep under control with weekly testing using pool test strips. They include:
  • pH level
  • Total alkalinity
  • Calcium hardness
  • "Free" chlorine (chlorine that hasn’t yet begun to dissolve)
  • Chlorine stabilizer
Let’s dive into the basics of what you need to know about these pool chemicals, along with the ideal pool water chemistry levels for each.
Ideal Pool Water Chemistry Levels
Total Alkalinity (TA):
Total Alkalinity (TA) is a crucial factor to balance in pool water because it directly affects the pH balance. The role of TA is to resist changes in pH when materials are added to the pool that could cause it to go up or down. When a substance is added to pool water that could alter the pH, TA reacts by neutralizing it and helps maintain the pH within the desired range. In essence, TA serves to keep the pH in check and prevent any drastic fluctuations that could lead to water balance issues.
Ideal TA range: 80-120 ppm
How to adjust TA: To increase TA, you can add an alkalinity increaser like sodium bicarbonate, while to decrease it, you can add muriatic acid or sodium bisulfate.
pH refers to the acidity, commonly measured on a scale of 0 to 14. A pH level below 7 means water is overly acidic, whereas a level approaching 8.0 renders water “basic” or alkaline. This works hand in hand with Total Alkalinity, which measures (in parts per million) alkali metals like sodium and potassium that occur naturally in pool water.
Ideal pH range: 7.4-7.6 ppm
Why pH balance matters: Maintaining proper pH balance is crucial to keep the water clean, clear, and safe for swimmers while protecting pool equipment. When pH levels are too low in a pool, the water becomes acidic, causing damage to pool equipment, skin, and eye irritation, making it difficult for chlorine to work effectively. When pH levels are too high, causing scale buildup, cloudy water, and irritation. It also makes it difficult for chlorine to sanitize the water.
How to balance pH: If you have fluctuating pH levels, it may be due to low Total Alkalinity. You can add baking soda to increase the alkalinity and stabilize the pH. However, it's important to follow recommended guidelines and not exceed the suggested dosage. If your pool's pH levels are too high, use a pH decreaser like sodium bisulfate or muriatic acid.
Calcium Hardness
Calcium hardness refers to the amount of dissolved calcium present in your pool water. Calcium enters your pool water from various sources such as tap water, pool chemicals, or debris like leaves and dirt.
Why calcium hardness matters: Low calcium levels can cause the water to become too soft, leading to foamy water, along with corrosion, etching, and damage pool surfaces and equipment. Meanwhile, high levels can cause calcium buildup and scaling and make the water cloudy.
Ideal calcium hardness range: 200-400 ppm
How to balance calcium hardness: To elevate calcium hardness levels, you may need to add calcium chloride (also known as a hardness increaser) to pool water. If your calcium hardness is too high, you may need to partially drain and refill your pool water to balance out the amount of calcium hardness in the pool.
Free Chlorine (FCL)
Free chlorine (FCL) refers to the amount of chlorine in a pool that has not yet mixed into the chlorinated water. Free chlorine, like pH level, is measured on its own scale.
Why free chlorine matters: Free chlorine is important because it actively sanitizes the pool water to prevent bacterial growth. Free chlorine is different from your chlorine stabilizer (cyanuric acid), discussed in more detail in the next section.
Ideal free chlorine range: 2.0-4.0 ppm
How to balance free chlorine: If free chlorine levels are low, add calcium hypochlorite or a pool shock treatment to bring them back into range. If free chlorine is too high, don’t add any more chlorine, and turn off any automatic chlorinators or chlorine floaters from the pool. Then, add a chlorine neutralizer (sodium thiosulfate) or chlorine remover (ascorbic acid) to the water. If you don’t plan on using the pool in the coming days, you can also try letting the chlorine naturally dissipate.
Chlorine Stabilizer (Cyanuric Acid)
Chlorine, in its purest form, is unstabilized, meaning it quickly degrades when exposed to sunlight. Chlorine stabilizers (also known as sanitizers) like cyanuric acid (CYA) slow the breakdown of free chlorine caused by UV exposure to prolong the sanitizing effects of free chlorine.
Ideal range for cyanuric acid: 30-50 ppm
Final Thoughts
It’s important to remember that deviations from acceptable ranges for chemicals (especially when first beginning the process of “opening” the pool after winter or a period of storms) are common and usually simple to correct. But pool chemistry problems typically reveal themselves in obvious ways. You just need to know what to look for and how to test and treat your water, and you’ll be good to go.
Your local pool professional can still be called in occasionally to ensure everything is in working order, or to even share their best tips for balancing your pool chemicals with ease. But by using the proper water testing tools and paying careful attention to your pool water, most pool owners manage just fine on their own. With practice, we’re willing to bet pool water testing will become second nature over time, helping you save money and get much more enjoyment out of your pool.
Find Your Pool Chemistry Essentials at Pool Supply Unlimited
At Pool Supply Unlimited, you’ll find everything you need to test, treat, and maintain your pool chemistry for a summer of safe swimming in clean, crystal-clear water. We even have the pool chemical feeders to make your chemical-balancing worries a thing of the past.
If you have more questions about water chemistry or need guidance on what chemicals you should get for your pool, we're here to help! For even more of today’s top pool supplies, including pool filters and handy pool maintenance items, check out our vast selection of pool supplies at the industry’s best prices. For more pool chemistry advice, feel free to comment below or give us a call for expert advice from one of our pool professionals.
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