In this guide: Adjust in the right order · Total alkalinity · pH · Free chlorine · Stabilizer (CYA) · Calcium hardness · Calculators
Balanced water is safe, clear, comfortable, and easy on your equipment. Five numbers describe it, and they interact — which is why the order you adjust them in matters as much as the targets.
Total alkalinity first (it buffers pH), then pH, then sanitizer (chlorine and its stabilizer), and finally calcium hardness. Fixing pH before alkalinity just means chasing your tail.
Alkalinity is the water's buffer: it absorbs acids and bases so pH doesn't swing wildly. Too low and pH bounces on every rain or dose; too high and pH gets "stuck" high and the water tends to cloud and scale. Raise it with sodium bicarbonate (baking soda), lower it with muriatic or dry acid.
pH decides how effective your chlorine is and how the water feels. The CDC's recommended range is 7.0–7.8; most operators hold 7.4–7.6. Below 7.2 the water turns corrosive and stings eyes; above 7.8 chlorine loses much of its punch and scale forms. Lower pH with acid, raise it with soda ash (sodium carbonate) or aeration.
Free chlorine is the active sanitizer. The CDC recommends at least 1 ppm in a stabilized pool and at least 3 ppm in a hot tub. Keep it steady rather than letting it crash and spike — a floating dispenser or feeder helps. Every dose is sized to your gallons, so an accurate volume is the foundation of all chemical dosing.
CYA is sunscreen for chlorine: without it, UV destroys free chlorine within hours. Around 30–50 ppm protects it outdoors. But too much CYA (often from over-using stabilized "trichlor" tablets) throttles chlorine's strength — the CDC advises against CYA in hot tubs entirely. If CYA creeps too high, the only real fix is partial draining and refilling.
Too little calcium and the water pulls it from plaster and grout (etching); too much and it deposits as scale. Vinyl and fiberglass pools tolerate a wider band than plaster.
These calculators turn the steps above into your exact numbers:
This guide is built on published health codes, national standards, and government energy guidance. For the exact equations behind the linked calculators, see our formula reference.
This guide is general information, not a substitute for your local health code or a licensed professional. Always follow the dosing instructions on your chemical labels and confirm readings with a test kit.