Complete Guide
The order you adjust pool chemicals matters more than most people realize. Here's the exact step-by-step process the pros use, simplified for any pool owner.
Most pool owners test their water, see that chlorine is low, and dump in chlorine. But if your pH is off, that chlorine won't work properly. If your alkalinity is off, your pH will keep swinging no matter what you do. Here's the correct order:
Target range: 80–120 ppm
Why it matters: Alkalinity is the foundation. It acts as a buffer that keeps your pH stable. If alkalinity is off, you'll chase pH adjustments all season and never win.
If too low:
Add sodium bicarbonate (baking soda). About 1.5 lbs per 10,000 gallons raises alkalinity by 10 ppm.
If too high:
Add muriatic acid or dry acid (sodium bisulfate). This lowers both alkalinity and pH.
💡 Wait 4–6 hours after adjusting before retesting. Run your pump the entire time.
Target range: 7.2–7.6 (ideal: 7.4)
Why it matters: pH controls how well your chlorine works and how comfortable the water feels. At 7.2, chlorine is about 65% effective. At 8.0, it drops to around 20%.
If too low:
Add soda ash (sodium carbonate). About 6 oz per 10,000 gallons raises pH by 0.2.
If too high:
Add muriatic acid. About 1 cup per 10,000 gallons lowers pH by 0.2.
💡 If you adjusted alkalinity with acid in Step 1, your pH may have already come down. Retest before adding anything.
Target range: 1–4 ppm (ideal: 2–3 ppm)
Why it matters: With alkalinity and pH in range, chlorine can actually do its job. Adding chlorine with bad pH is like throwing money in the pool.
If too low:
Add liquid chlorine, granular shock, or let your salt cell run. About 1 gallon of liquid chlorine per 10,000 gallons raises FC by 1 ppm.
If too high:
Wait. Sunlight and usage will bring it down naturally. Don't swim until it drops below 5 ppm.
💡 If total chlorine is more than 0.5 ppm higher than free chlorine, you have chloramines. Time to shock.
Target range: 200–400 ppm
Why it matters: Too low and the water eats your pool surface (etching). Too high and you get scale deposits on everything. Especially important for plaster and pebble pools.
If too low:
Add calcium chloride. About 1.25 lbs per 10,000 gallons raises calcium by 10 ppm.
If too high:
The only fix is partially draining and refilling with fresh water. There's no chemical that lowers calcium.
💡 Check your fill water's calcium level. Some areas have very hard tap water that raises calcium every time you top off.
Target range: 30–50 ppm (up to 70–80 for saltwater)
Why it matters: CYA protects chlorine from UV rays. Without it, the sun destroys about 90% of your chlorine within a few hours. But too much CYA blocks chlorine from working.
If too low:
Add cyanuric acid (stabilizer/conditioner). About 13 oz per 10,000 gallons raises CYA by 10 ppm. Dissolve first.
If too high:
Like calcium, the main fix is partial drain and refill. CYA reducers exist but are expensive and unreliable.
💡 If you use stabilized chlorine tablets (trichlor), they slowly add CYA every time they dissolve. Monitor this over the season.
| Chemical | Ideal Range | To Raise | To Lower |
|---|---|---|---|
| Total Alkalinity | 80–120 ppm | Baking soda | Muriatic acid |
| pH | 7.2–7.6 | Soda ash | Muriatic acid / dry acid |
| Free Chlorine | 1–4 ppm | Liquid chlorine / shock | Wait / sunlight |
| Calcium Hardness | 200–400 ppm | Calcium chloride | Drain & refill |
| Cyanuric Acid | 30–50 ppm | Stabilizer / conditioner | Drain & refill |
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