Pool Water 101: Chemicals, Testing & Balancing
Pool owners can face common issues like low alkalinity, high calcium hardness, or out-of-control algae blooms, especially after closing the pool for winter. A basic knowledge of pool water chemistry can help you correct these issues — or, better yet, avoid them altogether. That means you’ll save time and money, while getting more enjoyment out of the water. In this guide, we’ll cover balancing pool chemicals, which chemicals to use, best practices for safe chemical storage, and answer pool chemical FAQs.
Pool Water Chemicals
There are numerous types of chemical products that are formulated to clean or balance swimming pools or pool parts. For example, pool shock chemicals like calcium hypochlorite (cal hypo) and sodium dichloro-s-triazinetrione (di-chlor) are used to sanitize water—usually on a weekly or biweekly basis—by raising free chlorine levels.
Most pool chemicals fall into one of the following categories:
- Sanitizers: Disinfect the pool water
- Water Balancers: Used to adjust pH, alkalinity, calcium hardness, and chlorine levels
- Oxidizers: Can be used to supplement sanitizers
- Niche-Purpose Speciality Chemicals: These chemicals, like flocculants, help floating particles clump together for easier removal.
Learn More About Pool Water Chemicals
How to Test Your Pool Water Chemicals
There are three different ways you can test your pool water chemistry: using pool test strips, using a pool testing kit, or using an electronic device. Each method has pros and cons. First, let’s take a step-by-step look at the how-tos of each testing method.
Just remember: no matter which method you choose, it’s important to test and balance your water regularly — ideally, at least two or three times per week. Regular water testing will help ensure that your pool remains cloud-free, crystal-clear, and most importantly, safe to swim in.
Three Ways to Test Your Pool Water Chemistry
What is the Best Way to Test Pool Water?
No single method is “right” or “the best” — it’s simply a matter of finding what works for you. Many pool owners prefer the speed and simplicity of test strips, while others prefer using test kits, which do not need to be replaced as frequently.
Experts often recommend test strips for beginners, because they provide reliable results with minimal effort and cost. As you gain experience and become more comfortable with the water testing process, you’ll likely develop a preference of your own. In the meantime, the pool service experts at Latham are here to help answer all of your questions!
How to Balance Your Pool
Testing your water is only the first step—you’ll also have to balance it, depending on what needs adjusting. If you want to continue enjoying a clear, clean, and comfortable swimming pool, you need to know how to balance pool water.
By balancing your pool correctly, you can prevent pool corrosion, avoid skin and eye irritation, and protect valuable pool equipment from damage. To chemically balance your swimming pool water, follow these eight steps:
Step One
Adjust Alkalinity
A pool with low alkalinity has high acidity. If your swimming pool has alkaline levels below 80 ppm, it’s at risk of corrosion and damage — and worse, it’s unsafe for swimming. Fortunately, you can correct this problem by raising the alkalinity until it measures between 80 and 150 ppm, though some experts recommend a range of 80 to 120 ppm. To increase your swimming pool’s alkalinity, simply add the recommended amount of diluted sodium bicarbonate (baking soda). To lower the alkalinity, add dry or muriatic acid.
Step Two
Adjust pH Levels
If the pH levels are too low, the lining of your pool can become damaged, brittle, or stained. On the other hand, pH levels that are too high can cause cloudy water — and painful skin rashes. To avoid these issues, you need to balance your pool’s pH levels. You can raise your pool’s pH level by adding soda ash to the water. To lower your pool’s pH level, carefully add dry or muriatic acid while wearing protective gear over your eyes and hands. The best pH level for a pool ranges from 7.4 to 7.6.
Step Three
Balance Calcium Hardness
Most experts recommend using a calcium hardness increaser, such as calcium chloride, if your water’s calcium hardness levels fall below 200 or 150 ppm. If calcium hardness levels exceed 400 ppm, you can solve the problem by partially or completely draining and refilling the water. Anywhere from 200 ppm to 300 ppm is a good range to aim for.
Step Four
Sanitize
You can sanitize pool water with chlorine tablets, liquid or powdered chlorine, or even a salt chlorine generator. If the contamination is severe, you may need to shock the pool, which we’ll describe a little later. Ultimately, you are aiming for chlorine levels of 1 to 3 ppm, per current CDC recommendations.
Step Five
Measure Cyanuric Acid (CYA) Levels
CYA is a stabilizer that gets added to certain pool shocking chemicals, such as di-chlor. Its purpose is to prevent ultraviolet (UV) rays from burning off free chlorine, making sanitization more efficient — especially on hot, sunny days. The ideal CYA measurement for your swimming pool is between 35 and 60 ppm, unless you have a saltwater pool. In that case, aim for 60 to 80 ppm.
Step Six
Measure Dissolved Solids
Total dissolved solids, or TDS, measures how many solids (such as grime, salt, or algaecide) have dissolved in your pool water. Most experts recommend keeping your TDS levels below 1,500 ppm, or even below 1,200 ppm. If the TDS level is too high, you will need to fully or partially drain and replace the water.
Step Seven
Shock the Pool
Shocking your pool significantly increases the amount of free chlorine that’s available to destroy bacteria, algae, and chloramines. A weekly or biweekly shock helps to keep the water sanitized. Again, the optimal level of free chlorine is 1 to 3 ppm.
Learn More About Balancing Your Pool
Pool Water Chemistry Maintenance Checklist
Download our free maintenance checklist to get step-by-step instructions for testing your pool water chemistry and balancing your pool water.
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