High pH in a pool can cause a whole slew of annoyances; including cloudy water and algae

When I was a kid, I always wanted to live in a house with a pool but I grew up in the middle of nowhere where ponds were much more likely; you know, the kind with tons of algae, sandy bottoms, and murky water. While I still do not live in a house with a pool (I live in an apartment in Manhattan), my brother who lives nearby has both a pool and a house. He’s also the head of the chemistry department at a university, which comes in handy when maintaining a pool (who knew that pools involved so much chemistry). Pool owners, I’ve learned, spend a lot of time balancing pH and alkaline levels.

High pH in a pool can cause a whole slew of annoyances; including cloudy water and algae growth like the ponds of my childhood, as well as itchy eyes and skin and damage to pool parts.

PH refers to the “potential of hydrogen” of an aqueous solution; in this case: your swimming pool. It measures a substance’s acidity on a scale from 0 to 14. Anything below 7 is considered acidic while above 7 is termed “basic”. Chemistry defines a ‘base’ as any water solution of a chemical compound that has a lower hydrogen concentration than that found in pure water, such as ammonia. They contain ions, can conduct electricity, and feel slippery. Soapy water is one example. Bases and acids are chemical opposites.

To lower pH in a pool, you need to add more acid. The three acids used as pH decreasers include sodium bisulfate (dry acid), muriatic acid, and sulfuric acid.

Both sodium bisulfate and sulfuric acid add sulfates (indicated by their names) to your water that could cause other issues like corrosion of metal parts, degradation of a saltwater generator (if you have one), or damage to concrete. For these reasons, some experts recommend using muriatic acid above the other two.

This test kit contains 100 strips that measure the hardness, chlorine, bromine, free chlorine, pH, cyanuric acid, and alkalinity of your pool. Simply dip a strip into your pool, remove and carefully shake off excess water, then compare the colors with the chart on the side of the container.

Test your water for both alkalinity and pH levels. The total alkalinity of your pool affects the pH level, helping to keep it balanced - kind of like a good friend. If the alkalinity needs adjusted, do that first, then address the pH level.

In general, alkalinity should be somewhere around 80 and 120 parts per million (ppm) and the pH should be between 7.4 and 7.8. If the alkalinity is below what it should be but your pH is high, increase the alkalinity first by using sodium bicarbonate (baking soda). Adding 680 grams (or 1.5 pounds) of baking soda for every 10,000 gallons of water will raise the total alkalinity by 10 ppm without having much of an effect on the pH level. Products like Alkalinity Up and Alkalinity Increaser are essentially just baking soda with a fancier name.

Here are some quick, average alkalinity calculations per 10,000 gallons courtesy of my brother. Products made specifically for pool care will have dosage charts printed on the package.

On the other hand, if the alkalinity is too high, you can reduce both it and the pH by using sodium bisulfate or another pH reducer.

Calculate the volume of your pool in gallons so you can figure out how much acid you need to add.

For rectangle pools use: length x width x depth x 7.5 = volume in gallons

For round and ovals use: diameter x diameter x 5.9 = volume in gallons

Make sure to wear safety goggles and chemical-resistant gloves and long sleeves and pants when working with any of these acids. They are acids after all and you don’t want to get them in their concentrated state on your skin or in your eyes. Muriatic acid, or hydrochloric acid, specifically is very dangerous. Cover your body completely and wear a mask. Do not use it on a windy day.

Dissolve the acid in a 5-gallon bucket with clean water first if using a dry acid (or baking soda to raise alkaline).

Make sure to read the directions on the container to determine how much acid to add.

Some general measurements for 10,000 gallons are:

Pour the dissolved acid solution or the liquid acid if using muriatic or sulfuric acid into your pool around the edges with the pump running. Allow the solution to settle in and your pump to do its work for fifteen to thirty minutes, then retest the water. Repeat the process if needed.

Once the pH level is where it should be, check the alkalinity. If your alkalinity has fallen too low, use baking soda (as described above) to raise it again.

Rain, dirt, algae, and debris can affect the pH level so try and clean your pool weekly and make sure to test the water on at least a monthly basis. Water features will raise the pH level because movement speeds up aeration, or “outgassing” of carbon dioxide. As the CO2 leaves the water, the pH level goes up. Saltwater generators or chlorinators also create bubbles as they convert salt to chlorine which results in aeration.

If you replaster your pool that can cause a high pH level. New plaster releases calcium hydroxide for up to 30 days which has a pH level of 12 by itself.

Achieving the correct balance of chemicals in your pool water isn’t difficult as long as you stay on top of cleaning and testing. Sometimes, when I visit my brother we’ll sit out on his back patio near the pool while his kids swim and reminisce about our childhood and the farm ponds we grew up with. We were fearless then, swinging into our Grandma’s pond via a willow branch, digging our toes deep into the muddy, squishy bottom, and having what we called algae fights. I’m glad to have had those experiences – but I’m also equally glad to swim in a beautifully maintained, chemically balanced pool. It’s all about achieving balance, after all.