pH vs. Alkalinity: The Seesaw of Pool Chemistry
Why you can't fix one without understanding the other.
pH and Total Alkalinity are closely related, but they are not the same thing. pH measures the acidity or basicity of the water, while Alkalinity measures the water's ability to resist pH changes (its buffering capacity). Understanding this relationship is key to a stable pool.
The ideal pH for pool water is 7.4 to 7.6. This is the same pH as the human eye. If pH is too low (acidic), it causes eye sting and corrodes metal. If it's too high (basic), it causes cloudy water and makes chlorine much less effective at killing germs.
Total Alkalinity acts as a 'buffer' for pH. If your alkalinity is too low (below 80ppm), your pH will 'bounce' wildly with every rainstorm or chemical addition. If it's too high (above 150ppm), the pH will be difficult to move, often drifting upward and staying there.
FAQ
Should I adjust pH or alkalinity first?
Always adjust Total Alkalinity first. Because alkalinity acts as the buffer, getting it into the correct range makes it much easier to stabilize and maintain the correct pH level.