How to Balance Hot Tub pH and Alkalinity

Water balance is the part of hot tub care most people skip, and it's the reason a lot of tubs fight cloudy water, scale and itchy skin. Balanced water protects the heater, jets and shell, feels better on your skin, and lets your sanitizer do its job.

The target ranges

• Total alkalinity: about 80 to 120 ppm
• pH: about 7.2 to 7.8
• Calcium hardness: about 150 to 250 ppm

These are common ranges for home hot tubs. If your spa maker lists different numbers, go with theirs. Test two or three times a week with hot tub test strips; for chlorine tubs, the Leisure Time 4-way strips check chlorine, pH, alkalinity and hardness at once. New to strips? See how to use hot tub test strips.

Why you adjust alkalinity first

Total alkalinity acts like a buffer that holds pH steady. If alkalinity is too low, pH bounces around no matter what you add. If it's too high, pH keeps drifting up. Get alkalinity in range first, wait for the water to circulate, re-test, then fine-tune pH.

How to raise or lower alkalinity

• Too low: add an alkalinity increaser (usually sodium bicarbonate) made for spas. Browse water balance products.
• Too high: a pH reducer such as Spa Down lowers alkalinity and pH together. Add it in small doses and re-test.

How to raise or lower pH

• Too low (below about 7.2): water can be corrosive and irritating. Raise it with Spa Up.
• Too high (above about 7.8): sanitizer works poorly and scale and cloudiness get more likely. Lower it with Spa Down.

Tips that save chemicals

• Add one chemical at a time with the jets running, and wait for it to circulate before re-testing.
• Make small adjustments. It's easy to overshoot in a small volume of water.
• Jets and aeration push pH up over time, so a slow upward drift is normal.
• If your fill water is hard, a stain and scale control product helps keep calcium in solution, and a pH stabilizer like pH Balance Plus helps hold pH steady after a refill.

Shop pH, alkalinity and calcium products, or see the full weekly routine in our hot tub chemical guide. Next up: how to shock a hot tub.

Safety first: always follow the directions on the product label and your hot tub maker's manual. Add chemicals to the water one at a time, never mix chemicals together, and store them dry, cool and out of reach of kids and pets. Questions? Send us a message.