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Testing Your Pool Water

Proper water balance is the single most important factor to maximizing the life and appearance of any swimming pool. Frequently checking your pool water levels will help ensure proper maintenance.

It’s always a good idea to have a professional pool expert assess your water levels once per month to help you keep your water chemistry at an optimal level.

What Chemicals Do You Need for a Pool?

Most pool chemicals fall into sanitizers, water balancers, oxidizers, or niche-purpose categories.

Most pool chemicals fall into one of the following categories:

Pool shock chemicals are used to sanitize pool water that has been contaminated due to algae overgrowth, after heavy use, or after a storm that may have deposited debris into your pool.

There are two types of pool shock chemicals:

  • Chlorine-Based Pool Shock: This category includes cal hypo and di-chlor. Unlike cal hypo, di-chlor is stabilized with cyanuric acid (CYA), which helps protect chlorine against the sun.
  • Chlorine-Free Pool Shock: This category includes oxidizers like potassium monopersulfate, which helps sanitize pool water by preventing chloramines (combined chlorine) from forming.

Balancers are used to adjust pH, alkalinity, calcium hardness, and chlorine levels:

  • Alkalinity Increasers: Sodium bicarbonate (better known as baking soda) will boost your pool’s alkalinity levels while reducing the water’s acidity.
  • Calcium Hardness Increasers: These chemicals are designed to raise your pool’s level of calcium hardness. Consider using a calcium hardness increaser, such as calcium chloride, if your measurements drop below 150 parts per million (ppm).
  • Chlorine Neutralizers: According to the CDC, excessive chlorine can irritate your skin, eyes and lungs. It can also corrode pool equipment, potentially leading to costly damage. Chlorine neutralizers reduce the level of free chlorine in the water, helping pool owners avoid these problems.
  • pH Adjusters: You can raise or lower your pool’s pH levels by adding appropriate measurements of sodium carbonate (soda ash), sodium bisulphate (dry acid) or muriatic acid.

Algae growth doesn’t just make your pool water look unappealing – it poses several serious hazards. Algae can make surfaces slippery, increasing risks of slips or falls. It can also clog your pool’s filtration system and create a harmful environment, brimming with bacteria like E. coli. Damp, humid conditions – like a pool on a hot summer day – provide a prime breeding ground for algae, making it important to keep algae at bay. There are certain pool chemicals that can help you keep algae under control:

  • Phosphate Removers: Phosphate removers destroy phosphates, depriving algae of a critical food source.
  • Algaecides: Algaecides can help prevent algae from growing on pool surfaces.

Depending on the type of pool you own, there are other types of cleaning agents you may want to keep on-hand to keep your pool looking its best.

  • Filter Cleaners: Keep your pool filters clean and functional by using filter cleaners as necessary. These products break down oil, grime, and other obstructions.
  • Tile and Vinyl Cleaners: If you own a tile or vinyl liner swimming pool, you may want to look into cleaners to help maintain that day-one shine.

“Maintaining the proper chemical balance in your pool water not only keeps the water sparkling clean, but it also helps protect your heater, pump, and other system components from damage.”

How to Balance Your Pool

Testing your water is just the first step—you’ll also have to balance it to prevent corrosion, avoid skin and eye irritation, and protect your pool from damage.

To chemically balance your swimming pool water, follow these 7 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 & Dissolved Solids

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.

Total dissolved solids (TDS) measure 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 Six: Shock

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.

Step Seven: Test

Check your work by retesting the water, ensuring that alkalinity, pH, calcium hardness, and other measurements are within the acceptable range.

Contact a Trusted Pool Professional

Contact a Trusted Pool Professional

Ensure your backyard investment gets the care and protection it deserves.

Pool Water Chemistry Checklist

Download our free maintenance checklist to get step-by-step instructions for testing your pool water chemistry and balancing your pool water.

Pool Water Chemistry FAQs