You just got your pool filled, the equipment is running, and everything looks perfect. Now someone hands you a test kit and says "keep the water balanced." If your eyes glazed over — this guide is for you.
Water chemistry sounds complicated, but it really comes down to five numbers. Learn these, test regularly, and your pool will stay clear, safe, and easy to maintain. Ignore them, and you're looking at algae blooms, cloudy water, stained surfaces, and expensive equipment repairs.
This guide is written specifically for Florida pool owners. Our climate, water sources, and conditions are different from the rest of the country, and generic pool chemistry advice doesn't always apply here.
What Are the Ideal Pool Water Chemistry Levels?
| Parameter | Ideal Range | Sweet Spot |
|---|---|---|
| pH | 7.2–7.6 | 7.4 |
| Free Chlorine | 1–3 ppm | 2–3 ppm (FL) |
| Total Alkalinity | 80–120 ppm | 90–100 ppm |
| Calcium Hardness | 200–400 ppm | 250–350 ppm |
| CYA (Stabilizer) | 30–50 ppm* | 40 ppm |
*For salt chlorine systems, CYA of 60–80 ppm is recommended.
pH: The Foundation of Everything
pH measures how acidic or basic your water is on a scale of 0–14. Pool water should sit between 7.2 and 7.6, with 7.4 being the sweet spot — that's the same pH as human tears, which is why properly balanced pool water doesn't sting your eyes.
Too low (acidic, below 7.2): Corrodes metal fixtures, etches plaster and pebble finishes, irritates skin and eyes, and eats through your heater's heat exchanger. This is expensive damage.
Too high (basic, above 7.6): Chlorine becomes less effective (at pH 8.0, chlorine is only about 20% as effective), water gets cloudy, calcium deposits form on tile and equipment, and you'll see scaling on your salt cell if you have one.
How to adjust: Muriatic acid lowers pH. Soda ash (sodium carbonate) raises it. In Florida, you'll be adding acid more often than soda ash — our water naturally trends toward high pH, especially with salt systems.
Free Chlorine: Your Sanitizer
Chlorine is what kills bacteria, viruses, and algae in your pool. The "free chlorine" reading tells you how much active, working chlorine is in the water — as opposed to "combined chlorine" which has already been used up fighting contaminants.
The standard recommendation is 1–3 ppm, but in Florida we recommend staying at the higher end (2–3 ppm). Our heat, humidity, and year-round swimming season put more demand on chlorine than pools in cooler climates.
Too low (below 1 ppm): Algae starts growing. Bacteria levels become unsafe. Your pool goes from clear to green faster than you'd think — sometimes overnight in summer.
Too high (above 5 ppm): Skin and eye irritation, faded swimsuits, bleached hair. Most people start noticing the "chlorine smell" above 5 ppm (though that smell actually comes from chloramines, not free chlorine).
Total Alkalinity: The pH Buffer
Think of alkalinity as pH's bodyguard. It's a measure of your water's ability to resist pH changes. When alkalinity is in range (80–120 ppm), your pH stays stable. When it's low, your pH bounces all over the place — a condition called "pH bounce" that makes balancing your water feel impossible.
Too low (below 80 ppm): pH becomes unstable and hard to control, water becomes corrosive, and you'll find yourself adding acid or soda ash constantly.
Too high (above 120 ppm): pH tends to drift high and become difficult to bring down, water gets cloudy, and scaling increases.
How to adjust: Sodium bicarbonate (baking soda) raises alkalinity. Muriatic acid lowers it. Always adjust alkalinity before trying to fix pH — getting alkalinity right often fixes pH on its own.
Calcium Hardness: Protecting Your Surfaces
Calcium hardness measures the dissolved calcium in your water. The ideal range is 200–400 ppm. This one matters more than people think, especially for the longevity of your pool's interior finish.
Too low (below 200 ppm): Water becomes "hungry" for calcium and will pull it from your plaster, pebble finish, or grout. This etches and degrades your surfaces over time. On a new pool with a $10,000+ finish, that's a problem.
Too high (above 400 ppm): Calcium deposits form on tile, inside pipes, and on your salt cell. You'll see white, crusty buildup that's hard to remove. Florida well water is notorious for high calcium — if you're on well water, this is one to watch from day one.
How to adjust: Calcium chloride raises it. Lowering calcium hardness is harder — you may need to partially drain and refill with softer water, or use a sequestrant to keep the calcium in solution.
CYA (Cyanuric Acid) / Stabilizer: Sunscreen for Chlorine
CYA protects your chlorine from being destroyed by UV light. Without it, the Florida sun would burn through your chlorine in about 2 hours. With proper CYA levels (30–50 ppm for traditional chlorine, 60–80 ppm for salt systems), your chlorine lasts all day.
Too low (below 30 ppm): You're wasting chlorine. The sun destroys it faster than your system can produce it. You'll be adding chlorine constantly and still struggle to maintain levels.
Too high (above 80–100 ppm): CYA starts "locking up" your chlorine, making it less effective even though your test reads normal levels. This is the most common cause of algae in pools that "should" be fine based on chlorine readings. The only way to lower CYA is dilution — partially draining and refilling.
"CYA buildup is the number one water chemistry mistake we see in Florida pools. Stabilized chlorine tablets (trichlor) add CYA every time you use them. Over months, it creeps up silently until your chlorine stops working."
Why Is Pool Chemistry Different in Florida?
If you've read pool chemistry guides written for the entire country, you've probably gotten advice that doesn't quite work here. Florida's climate — especially in the Sarasota, Bradenton, and Lakewood Ranch area — creates unique challenges:
1. Heat Burns Through Chlorine Fast
When water temperature is above 85°F — which is most of the summer here — chlorine gets consumed faster. Bacteria and algae are also more active in warm water. During June through September, expect to use 30–50% more chlorine than the rest of the year. If you have a salt system, you may need to turn up the output percentage.
2. Afternoon Thunderstorms Dilute Everything
Florida's daily summer rain adds fresh water to your pool, which dilutes your chemicals and typically drops your pH. A heavy afternoon storm can swing your chemistry noticeably. This is why testing after rain events matters. Don't just assume your levels are fine because you tested two days ago.
3. Well Water Is High in Minerals
Many homes in Manatee, Sarasota, and Charlotte counties are on well water. Well water in this region is often high in calcium, iron, manganese, and other dissolved metals. If you're filling or topping off your pool with well water, you may need a metal sequestrant (like CuLator or Jack's Magic) to prevent staining. Get your fill water tested separately — knowing what's in it saves headaches later.
4. High Humidity Promotes Algae Year-Round
In drier climates, pools get a break from algae pressure in the winter. Not here. Florida's humidity means algae can grow 12 months a year. Keep your chlorine and CYA in range even in the "off-season" — there really isn't one for Florida pool chemistry.
5. Salt Systems Need CYA Monitoring
Salt chlorine generators produce unstabilized chlorine, which is great — it means CYA doesn't build up automatically like it does with trichlor tablets. But it also means you need to add CYA separately and monitor it. Without CYA, your salt cell works overtime to keep up with UV breakdown, which shortens the cell's lifespan and costs you money. For a full breakdown of salt vs. traditional chlorine, see our salt chlorine vs. traditional chlorine comparison.
How Often Should You Test Pool Water in Florida?
Test your water at least twice a week during the swimming season (which is most of the year in Florida). Here's what to test and when:
Twice a Week (Quick Test)
- Free Chlorine — make sure it's 2–3 ppm
- pH — make sure it's 7.2–7.6
This takes 60 seconds with test strips or a basic liquid kit. Do it before adding any chemicals.
Weekly (Full Test)
- Free Chlorine
- pH
- Total Alkalinity
Monthly (Deep Test)
- Everything above, plus:
- Calcium Hardness
- CYA / Stabilizer
- Salt level (if you have a salt system)
For the monthly test, we recommend either a Taylor K-2005 liquid test kit (the gold standard for accuracy) or taking a water sample to your local pool supply store. Most stores will test it for free.
Test Strips vs. Liquid Kits
Test strips are fast and convenient — dip and read in 15 seconds. They're good enough for your twice-weekly chlorine and pH checks. But they're less accurate for alkalinity, calcium, and CYA.
Liquid test kits (like the Taylor K-2005 or K-2006) use reagent drops and color matching. They're more accurate but take a few minutes. Use these for your weekly and monthly full tests.
What Pool Chemicals Should You Keep on Hand?
- Muriatic acid — for lowering pH and alkalinity (you'll use this the most)
- Sodium bicarbonate (baking soda) — for raising alkalinity
- Calcium chloride — for raising calcium hardness
- CYA / Stabilizer — for protecting chlorine from UV (especially important for salt systems)
- Pool shock (cal-hypo or liquid chlorine) — for periodic superchlorination
- Algaecide — preventative dose weekly, or a stronger dose if you see any green
Store chemicals in a cool, dry, shaded area. Never stack different chemicals near each other — some react dangerously if they mix. And always add chemicals to water, never water to chemicals.
What Are the Biggest Pool Chemistry Mistakes?
1. Not Testing Often Enough
"I test once a month" is how pools turn green between tests. In Florida's heat, things change fast. Twice a week for chlorine and pH is the minimum. After rain, after a pool party, or after any heavy use — test again.
2. Adding Chemicals at Midday
The sun destroys chlorine. If you add chlorine or shock at noon, you lose a significant portion to UV before it can do its job. Always add chemicals in the evening after sunset, or very early morning. This gives the chemicals hours to circulate and work before the sun comes back.
3. Ignoring CYA Until It's Too High
CYA builds up slowly if you're using stabilized chlorine tablets (trichlor). By the time you notice a problem, your CYA might be 120+ ppm and your chlorine is effectively useless. Test CYA monthly and track the trend. If it's climbing above 70–80 ppm (for salt systems) or 50 ppm (for traditional), it's time to partially drain and refill.
4. Shocking With the Cover On
Shock (superchlorination) produces gases that need to off-gas. If your pool has a solar cover or a solid cover and you shock without removing it, those gases get trapped, concentrating near the water surface. This can damage your cover, bleach anything it touches, and create an unpleasant situation when you lift it. Remove the cover before shocking, and leave it off for at least 8 hours.
5. Over-Relying on the Salt System
Salt chlorine generators are excellent — we recommend them for most builds. But they're not magic. You still need to monitor pH (salt systems tend to raise it), still need CYA, still need to check alkalinity and calcium, and still need to shock periodically after heavy use or rain. The salt system handles daily chlorination. Everything else is still on you.
When Should You Call a Pool Professional?
Most water chemistry is manageable for homeowners. But there are times when calling a pool service company or bringing us a water sample makes sense:
- Persistent algae that doesn't respond to shocking — could be a CYA problem, a circulation issue, or resistant algae strain
- Metal staining (brown, green, or purple stains on surfaces) — needs professional diagnosis and treatment
- CYA above 100 ppm — you need a drain-and-refill plan
- Consistently cloudy water despite balanced chemistry — could be a filtration or circulation problem
- New pool startup — the first 28 days of a new plaster or pebble finish require specific chemistry protocols to cure properly
We include a pool school session with every build — we literally stand at your pool with you and walk through testing, chemicals, equipment, and a maintenance schedule. It's the single best thing you can do as a new pool owner. For a month-by-month breakdown of what to do when, check out our year-round pool care schedule. And make sure you're up to speed on Florida pool safety requirements as well.
Frequently Asked Questions
What should pool chlorine levels be in Florida?
Free chlorine should be between 1 and 3 ppm, but in Florida's heat we recommend staying at the higher end (2-3 ppm). Warmer water and year-round sun put more demand on chlorine than pools in cooler climates.
How do I lower pH in my pool?
Add muriatic acid to lower pH. In Southwest Florida, you'll use acid more often than soda ash because our water and salt systems both tend to push pH upward. Always test before and after adjusting.
Why does my pool keep turning green even with chlorine?
The most common cause in Florida pools is high CYA (cyanuric acid) levels. When CYA climbs above 80-100 ppm, it "locks up" your chlorine so it can't kill algae effectively, even though your test shows normal chlorine readings. The fix is a partial drain and refill.
How often should I shock my pool in Florida?
Most Florida pools benefit from shocking every 1-2 weeks during the summer and after heavy rain or pool parties. Always shock in the evening so the chlorine has time to work before the sun breaks it down.
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- Ideal water chemistry ranges: Pool & Hot Tub Alliance (PHTA) guidelines
- Chlorine effectiveness and pH: CDC — Model Aquatic Health Code (MAHC)
- Florida well water mineral content: Southwest Florida Water Management District (SWFWMD)
- Salt chlorine generator maintenance: Hayward, Pentair, and Zodiac manufacturer guidelines
This guide provides general water chemistry recommendations for residential swimming pools in Florida. Specific conditions vary by water source and pool type. Always follow your equipment manufacturer's recommendations and consult a pool professional when in doubt.