Just as Olivia Pope safeguards people from scandal, alkalinity shields your pool’s pH from anything that can throw it out of whack, like swimmers, pool toys, debris, and heavy rain. Total alkalinity helps maintain an ideal pH (between 7.4 and 7.6) — all of which make for an optimal swimming environment. When the alkalinity of your pool plunges deeper than your friends off the diving board, though, you’ll need to know how to raise the alkalinity in your pool.
Consider things handled with an arsenal of help: a pool chemistry test kit/test strips and the right amount of baking soda.
But First, What is Alkalinity in a Pool?
Total alkalinity (aka your pool’s pH bestie) is what keeps those pH levels in check, preventing wild fluctuations up and down the pH scale, no matter what the world — or your pool party guests — throws at it. How? Cyanuric acid (an alkaline substance) enters the water through the pool stabilizer, keeping pool alkalinity levels where they should be. When your swimming pool suffers from low alkalinity levels, your pool’s pH will get thrown off and become difficult to rebalance.
Maintaining the ideal range of total alkalinity, 80 to 120 parts per million (ppm), is important to keeping your pool’s pH levels between 7.4 and 7.6. Any lower than that, and your pool will be too acidic; acidic water can cause cloudy water, corrosion of pool equipment and pool surfaces, eye and skin irritation for swimmers, and it can lessen the effectiveness of chlorine.
What Causes Low Alkalinity?
A few things can send your total alkalinity levels on a downward spiral, including:
- overall low pH
- heavy rain/storm
- shocking your pool too frequently
- heavy pool use/excess sweat and urine from swimmers
- too much muriatic acid
How to Raise the Alkalinity in a Pool
1. Test the Pool Water
As part of your weekly pool maintenance, test the chemistry of your swimming pool water. For the most accurate reading, a full test kit is recommended. Your kit should include a collection tube and three alkalinity reagents. Here’s how to use the kit:
- Holding the tube in your hand, submerge it in the pool elbow-deep.
- Add two drops of the first reagent and swirl to mix; then, add five drops of the second.
- You’ll know things are mixed well when the water sample turns green.
- Add one drop at a time of the third reagent, counting how many drops it takes to turn the water red.
- Then, multiply that number by 10; this is your alkalinity measurement in parts per million (ppm). Remember, the ideal range is between 80 and 120 ppm.
You can also use test strips for a quicker, math-free reading. Simply dip the strip elbow-deep and set it aside and away from the sun for about 15 seconds. Then, match your water color with the included color chart to determine your total alkalinity level.
2. Adjust the Alkalinity Levels
If your test comes back with a reading of less than 80 ppm, you’ll need to raise alkalinity with an alkalinity increaser, which is just a super fancy way of saying use baking soda (aka sodium bicarbonate). Baking soda will raise the alkalinity of your pool water without raising the pH too much.
Depending on the size of your pool and the amount needed to raise the alkalinity of your pool to be between 80 and 120 ppm, you could use anywhere from 1.5 to 10 lbs of baking soda. A general rule of thumb is for every 10,000 gallons of water, add 1.5 lbs of baking soda. This will raise alkalinity by 10 ppm, helping you gradually adjust the pool chemicals, so as not to upset any other balance.
Once you’ve measured the correct amount, scatter the baking soda across the pool water, so it doesn’t end up settling in one spot — keeping your pool pump running will also help circulate the product. (Some experts say to add baking soda into the skimmer to help distribute it throughout the pool; others disagree, saying that doing so can actually mess up your chlorinator.)
3. Retest the Pool Chemistry
After giving the baking soda about six to eight hours to work, retest the water. If levels still aren’t where they need to be, add more baking soda to raise alkalinity even more. Be careful not to overdo it on the chemical dosing, though, as that can lead to alkalinity levels that are too high.
When alkalinity isn’t stable, neither is your pH. A lower pH can contribute to corrosion, while a high pH can limit sanitization efficacy/drop free chlorine levels.
FAQ About Alkalinity in a Pool
High alkalinity can cause pool problems, too; specifically, it can lead to cloudy water and calcium buildup — that unsightly white scale that can potentially harm your pool filtration system. After testing your water chemistry, if your total alkalinity is more than 120 ppm, reduce it by adding muriatic acid or dry acid (sodium bisulfate).
Technically, yes. By itself, alkalinity doesn’t make a pool safe or unsafe to swim in — it’s the side effects high alkalinity can cause that can make the water less desirable. Besides the things mentioned above, high alkalinity can make chlorine’s sanitation power ineffective, and the potentially similarly high pH may cause chemical burns, skin rashes, and eye irritation, depending on how extreme the levels are. The best bet? Keep all water chemistry the correct balance.
Pretty much the reverse of each other, baking soda (sodium bicarbonate) works to raise alkalinity while only slightly elevating pH levels, while soda ash (sodium carbonate) works to raise pH while only slightly elevating alkalinity.
When to Hire a Pool Cleaning Pro
Knowing how to adjust pool chemistry is something all pool owners should understand. However, if you’re sensitive to pool chemicals, afraid of messing things up, or just don’t want to do any pool maintenance yourself, enlist the help of a local pool professional. They’ll calculate pool water levels for you, and adjust them as needed.