How to Quickly Lower pH in Your Pool

    Ways to Test the pH in swimming pool

    There are many ways to know how to test the pH of your swimming pool. However, here I will not detail how to check, but just give you some tools to speed up the process.


    pH test strips – These are the most common and easiest way to test pool pH. They're inexpensive and easy to use. Simply dip the strip in the water and compare the color to the chart on the bottle. The strips have a margin of error of +/- 0.3 to 0.5 pH.

    Digital pH meter – A more accurate option is a digital pH meter. They have a probe that you submerge in the water and the meter will show the exact numeric pH reading. They have a margin of error of +/- 0.1 pH. They typically need to be calibrated periodically.

    Taylor test kit – A liquid test kit using chemicals and color charts for a more accurate reading. You'll add chemical reagents to a water sample and then compare the resulting color to the color chart, which corresponds to a pH value. They typically have a margin of error of +/- 0.2 pH.

    Swimming pool test strips – Similar to pH test strips but also test for other pool parameters like alkalinity, chlorine levels, etc. They're convenient but not as accurate as other options.


    How to Quickly Lower pH in Your Pool

    We've put together ways you can absolutely do at home to lower the pH of your pool.

    1. Add dry acid or liquid muriatic acid

    This is the fastest way to lower pool pH. The active ingredient in the dry acid is sodium bisulfate. You also see it marketed as a pH reducer or pH down, and the sodium bisulfate I'm using today is from the swim. 

    They also sell sodium bisulfate in bags and for safe handling you can see inside the bucket it also comes in a bag. There are many benefits of using dry acid over liquid muriatic acid. The dry acid is safe to handle and won't burn your skin and no fumes.

    It's also not a very strong oxidizer like muriatic acid. So won't rust all the metal around your house. It also has a longer shelf life than muriatic acid. 

    And even though it's a little more expensive to use a dry acid to lower your pH in total acclivity, it is a very Safeway to do it. So the safety factor definitely outweighs the cost and you'll need a few things. 

    When you're using dry acid:

    • You're going to need some kind of measuring cup or scoop to measure the amount of dry acid you're going to be adding to your pool

    • You'll need a 5-gallon bucket to premix a dry acid with water and mix them well

    • Pay attention to the manufacturer's recommendations listed on the dry acid tank, often manufacturers rely on a specific volume of water such as 5,000 or 10,000 gallons to make their recommendations

    • You can also use an online calculator to get the exact amount of sodium bisulfate to add to your pool to lower the pH or based on the table above

    • Add the acid directly to the pool and circulate the water with the pool's pump and filter. Start with small amounts and retest the pH after each addition

    2. Run the pool filter continuously 

    Running your pool filter non-stop is a good way to gradually lower the pH in your pool water. By keeping the water circulating and getting filtered 24/7, you slowly deplete the pool's alkalinity. Since high alkalinity buffers against changes in pH, lowering alkalinity makes it easier for acid to reduce the pH to the proper range.

    The constant filtration also exposes those alkaline minerals so they can be captured in the filter. Over 1-2 days, you'll start to notice the pH dropping bit by bit. Keep checking it daily so you can see how quickly it's decreasing.

    3. Use chlorine tablets

    Chlorine tablets can help speed up the pH-lowering process and keep the pool sanitized while you work on getting the pH in range. Place the chlorine tablets in the skimmer or floating dispenser.

    4. Perform a partial pool drain

    If the pH is extremely high, partially draining the pool (about 25-50%) and refilling it with acid water can help get the pH down quicker. However, this method wastes a lot of water.

    5. Shock the pool with chlorine

    Adding chlorine shock treatment boosts the sanitizer level which can help lower pH, especially when combined with acid additions and continuous filtration. But pH will likely creep back up within a few days.


    Causes of too high pH in a pool

    The most common reason your pool's pH is too high is excess alkaline salts in the water. These natural alkaline minerals act as a buffer, resisting changes to the pH level.

    When the alkalinity gets too high, it takes more acid to actually lower the pH. So the first step is bringing the alkalinity into the proper range for your pool.

    Other factors that can push your pH higher than desired:

    • Sun exposure: While sunshine breaks down chemicals that lower pH a bit, the main problem is evaporation. As water evaporates, it leaves behind more of those alkaline minerals that raise the pH.

    • Hard water: If your fill water has a lot of calcium and magnesium minerals, they'll gradually accumulate in your pool over time and drive the pH up.

    • Infrequent acid additions: If you don't add acid often enough or in large enough amounts to counteract the pool's natural alkalinity, the pH will just keep creeping up.

    • Plaster and concrete pools: Over the years, the actual pool surfaces can release alkalizing compounds into the water, raising the pH slowly

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