Pool Chemistry Basics: How to Balance Your Water Like a Pro

What's happening to my pool?

—Does your pool water turn cloudy, green, or just feel "off"—even when you add chlorine?
—Are your test strips showing confusing results like low pH, high stabilizer, or strange numbers you don’t understand?
In this beginner-friendly guide, you’ll learn the 7 key water chemistry factors that every pool owner needs to understand.
We’ll explain each factor—what it is, what makes it go up or down, and what to do about it—in simple, clear language with real-life examples.  Tuning you into a Pool Pro

Wait!

Before you begin, we assume your filter is clean; otherwise, achieving the expected results will be more challenging, as inadequate circulation is crucial for maintaining a proper water balance. If your filter appears like the one in this picture, you need to replace it, especially in older pools, which can be more challenging due to the overall condition of the system.

What Is Water Balance—and Why Does It Matter?

Water balance refers to maintaining your pool water in a safe, clean, and stable condition. When water is balanced, it:

• Feels better on skin

• Helps chlorine work effectively

• Prevents damage to your pool surfaces and equipment

• Keeps your water clear and comfortable

The 7 chemistry factors we’ll cover:

1. pH

2. Total Alkalinity (TA)

3. Calcium Hardness (CH)

4. Cyanuric Acid (CYA)

5. Total Dissolved Solids (TDS)

6. Combined Chlorine (CC)

7. Phosphates

1. pH: The Foundation of Pool Balance

What it is:

pH measures how acidic or basic your water is. The scale ranges from 0 (very acidic) to 14 (very basic), with 7 being neutral. Pool water should stay between 7.4 and 7.6. We like 7.5 to be our goal.

Why it matters:
If your pH is too high or low, chlorine doesn’t work right—and your pool might get cloudy or irritating to swim in.

What raises pH:

• Splashing, waterfalls, or spa jets (they add air to the water)

• Saltwater systems

• Some chemicals like soda ash

What lowers pH:

• Acid (like muriatic acid or dry acid)

• Stabilized chlorine (like trichlor or tablets)

• CO₂ systems

Quick Tip:
Control alkalinity first—then pH is easier to manage.

2. Total Alkalinity (TA): The pH Bodyguard

What it is:
TA helps your pH stay steady and avoid fluctuations. It’s made mostly of bicarbonate.

Good range: 90–110 ppm

What raises TA:

• Adding baking soda (sodium bicarbonate)

• Some types of fill water

What lowers TA:

• Adding acid

• Rain, leaks, or splashing that removes or dilutes the pool water

• Reverse osmosis (RO) filters are typically used for drinking water and are installed between the cold water source and the pool. While adding one of these filters to a pool is generally not discussed or practiced in our industry, it is highly recommended.

3. Calcium Hardness (CH): The Pool’s Bone Strength

What it is:
CH measures how much calcium is in your water. Your pool needs some—but not too much.

Good range: 250–400 ppm (depends on your pool surface but let's stick to plaster pools)

What raises CH:

• Adding calcium chloride or cal hypo

• Using hard tap water

• Water "grabbing" calcium from plaster or tile grout if it's unbalanced

What lowers CH:

• Diluting the pool with soft water (like rain)

• RO filtration

• Forcing calcium to form dust and vacuuming it out (last resort)

Watch out for:
White scale, cloudy water, or rough surfaces.

4. Cyanuric Acid (CYA): The Chlorine Shield

What it is:
CYA (also called a stabilizer or conditioner) protects chlorine from being destroyed by sunlight / UV rays.

Good range: 30–50 ppm

What raises CYA:

• Adding it directly (granular or liquid)

• Using stabilized chlorine (trichlor or dichlor tabs/shock)

What lowers CYA:

• Draining and refilling

• RO filtration (Reverse Osmosis)

• Letting it slowly break down (takes months)

• Special CYA-removing products (some work, some don’t)

Important:
Too much CYA weakens chlorine—even if your test says it’s “enough.”

5. Total Dissolved Solids (TDS):

The "Everything Left Over"

What it is:
TDS includes all minerals, salts, and chemicals that have built up in your pool over time. Basically old water

Why it matters:
High TDS can make your pool cloudy and harder to balance—even if all your test results look good.

What raises TDS:

• Adding chlorine, salt, calcium, or stabilizer

• Replacing evaporated water with tap water

What lowers TDS:

• Draining and refilling

• RO filtration, Ozone, and UV systems help, too.

Pro Tip:
If your water looks dull but everything tests okay—check your TDS.

6. Combined Chlorine (CC): The Used-Up Chlorine

What it is:
CC is chlorine that has already reacted with sweat, pee, or ammonia. It’s no longer working—and smells bad!

Good level: 0 ppm (or as close as possible)

What raises CC:

• People peeing or sweating in the pool

• Ammonia-based products (like some algaecides or cleaners)

• Certain tap water sources

What lowers CC:

• Shocking the pool (breakpoint chlorination)

• Using enzymes

• Secondary systems like UV, ozone, or AOP

• RO filtration

Remember:
Chlorine smell ≠ clean. It might mean you need to remove combined chlorine.

7. Phosphates: The Algae Food

What it is:
Phosphates are nutrients that algae love. Even though phosphates don’t “use up” chlorine, they help algae grow—which then does use up chlorine.

What raises phosphates:

• Tap water

• Leaves, grass, dirt

• Pool chemicals (like stain inhibitors)

• Swimmers (yes, humans carry phosphorus too!)

What lowers phosphates:

• Using a phosphate remover

• RO filtration

• Diluting the pool with cleaner water

Tip:
Keep phosphate levels under 500 ppb to help chlorine do its job.

Wrap-Up: How to Keep It All in Balance

Balancing pool water may seem tricky—but once you understand each factor and how they connect, it becomes way easier. Here's a simple order to follow when testing and fixing your pool chemistry:

1. Start with Total Alkalinity (TA)

2. Adjust pH

3. Then check Calcium Hardness (CH)

4. Test Chlorine and CYA

5. Keep an eye on Phosphates, TDS, and CC weekly

You may be asking yourself what test Kit to buy that can do all this right?

In this next article, we present the best-in-class comparisons and our recommendations based on customer feedback. 

Now that you understand the 7 pillars of pool water balance, your job is simple:

• Test your water weekly

• Make one small change at a time

• Use this guide to understand what the numbers mean—and what to do next

And remember: If your pool water is balanced, your chlorine can focus on keeping it clean.

Need Help?

At J Designs, our Service Division helps pool owners like you resolve water issues without the hassle. Contact us for personalized assistance, water testing tools, or professional balancing services.

Watch this video to prevent pool problems.