Check pool chemistry

Test and balance your pool water to keep it safe and clear for swimming.

Why it matters#

Proper pool chemistry prevents algae, bacteria growth, and equipment corrosion. It also protects swimmers from skin and eye irritation.

What you'll need#

Tools#

• Pool test kit or test strips
• Pool skimmer

Materials#

• pH increaser or decreaser (as needed)
• Chlorine or other sanitizer (as needed)
• Alkalinity increaser (as needed)
• Stabilizer/cyanuric acid (as needed)

Steps#

1. Clear surface debris#

Use a skimmer to remove leaves and floating debris before testing. This ensures accurate readings.

2. Collect a water sample#

Dip your test kit vial or strip about 18 inches below the surface, away from jets and skimmers. This gives a representative sample.

3. Test chlorine level#

Follow kit instructions. Ideal free chlorine: 1-3 ppm. Below 1 ppm allows algae and bacteria growth; above 5 ppm can irritate skin and eyes.

4. Test pH level#

Ideal range: 7.2-7.6. Low pH (acidic) corrodes equipment and irritates skin. High pH reduces chlorine effectiveness and causes cloudy water.

5. Test total alkalinity#

Ideal range: 80-120 ppm. Alkalinity stabilizes pH—if it's off, pH will be hard to control.

6. Test cyanuric acid (stabilizer)#

Ideal range: 30-50 ppm. Stabilizer protects chlorine from UV breakdown. Too high reduces chlorine effectiveness.

7. Adjust chemicals as needed#

Add chemicals one at a time, waiting 4-6 hours between adjustments. Follow product instructions for dosing based on pool volume.

8. Retest after adjustments#

Wait at least 4 hours (or overnight) after adding chemicals, then retest to confirm levels are in range.

Pro tips#

• Test 2-3 times per week during swimming season, daily during heavy use
• Test at the same time each day for consistent readings—morning is ideal
• Keep a log of readings to spot trends and catch problems early
• Replace test strips/kit reagents annually—old supplies give inaccurate readings

Warnings#

• Never mix pool chemicals directly—add each separately to the pool
• Add chemicals to water, not water to chemicals (especially for acids)
• Store chemicals in a cool, dry place away from each other and direct sunlight
• Never swim immediately after adding chemicals—wait as directed on product labels

When to call a pro#

Contact a pool service if you can't get chemistry balanced after multiple attempts, notice algae that won't clear, have cloudy water despite proper chemistry, or need help with opening/closing the pool seasonally.