How to Lower pH in Pools in 5 Simple Steps

Need to learn how to lower the pH in your pool? There’s no need to pull out the old chemistry textbook but remember you don’t want your pH to be too high or low. To make your summer swims enjoyable and ensure chlorine in your pool can work effectively, there's an optimal range you'll want to keep your pH in. Here’s how to lower the pH level in your pool in under four hours.

Why Should I Lower My Pool's pH?

Alkalinity, acidity levels … there’s no need to get hung up on terms. The most important reason you should lower your pool's pH is that chlorine, the main chemical in your pool, won't work as well in high pH water.

Chlorine is responsible first and foremost for sanitation and warding off bacteria. So if your water is more alkaline than it should be, you could inadvertently be exposed to bacterial diseases, such as salmonella and E.coli, according to The International Association of Certified Home Inspectors.

Lowering your pool's pH will also help:

• Eliminate cloudy water

• Prevent scale buildup or corrosion on pool equipment (railings, stairs, etc.)

• Reduce algae buildup on the surface or floor of your pool

It will also help prevent infections, such as swimmer's ear and rashes, according to the Centers for Disease Control and Prevention (CDC).

A pool's pH level should range between 7.2 and 7.8 (on the pH scale of 1 to 14) with a free chlorine level of 80 to 120 parts per million (ppm). A high pH outside of this range means your pool water is more alkaline than it should be. 

How Much Does It Cost to Lower a Pool's pH?

It costs anywhere from $5 to $40 to lower your pool's pH doing it yourself. You'll need to invest in a bag (or several bags of pH reducer, which costs about $1.50 to $2 per pound. You might also want to invest in a liquid pH testing kit over the disposable strips, which runs about $15.

If your pool's pH levels are routinely high, it could also be a good idea to invest in a larger bucket of pH reducer to save on per-pound costs. You can find them at pool stores in sizes as large as 25 pounds.

Understanding Alkalinity and pH Levels 

The pH (power of hydrogen) level of water tells you how acidic or basic it is. Remember that pH is on a scale of 0 to 14, with 0 being acidic and 14 being basic. If water has a pH of 7, it’s neutral. When measuring the pH level in water, you’re calculating the amount of hydrogen. 

Tap water, for example, should have a pH between 6.5 and 8.5. Water with a pH over 7 is alkaline—while this sounds like water alkalinity, the two are very different.

Alkalinity is measured in parts per million (ppm) and measures how much alkaline substances are in the water. The alkaline substances in pools are carbonate, bicarbonate, and hydroxides. These substances help stabilize your water’s pH by neutralizing bases and acids, making it easier to maintain proper pH levels. You’ll want to keep the total alkalinity of your pool between 80 and 120 ppm.

In summary, the ideal levels are as follows: 

• Pool water pH: 7.2–7.8

• Free chlorine level: 80–120 ppm

• Total alkalinity in pool water: 80–120 ppm

Signs of High pH in Swimming Pools

Thinking the pH in your pool might be too high? The only way to know for sure is to test, but there are some telltale signs to look out for.

Here are some signs of high pH levels in pools:

• Rashes, swimmer's ear, or in more extreme situations, bacterial infections, such as salmonella or E.coli

• Cloudy water

• Algae buildup on the surface of your pool

• Scale formation

• Corrosion of pool

How to Lower pH in Pools

If you’re ready to get back to carefree days spent in the pool, use these steps to lower pH levels. You can troubleshoot with this same guide in the future if issues resurface.

1. Clean Your Pool 

If your pool is dirty, you might not get an accurate reading. For example, leaves, dirt, sticks, and even sunscreen buildup on the surface can all raise your pool’s pH level.

Remove debris floating on the surface or hanging out at the bottom of your pool. If the pool is especially dirty, you might want to hire a local pool service company to take care of it. 

2. Test Your Pool’s pH

Use a pool pH testing kit (either strips or a water testing kit) to establish a baseline. Liquid pH testing kits are more accurate than strips, according to the Centers for Disease Control and Prevention. If the number is higher than 7.8, you’ll want to lower the pH of your pool.

3. Make Sure Your Pool’s Filtration System Is Working 

Double-check that your pool's filter is working correctly. Is water flowing through it properly? Is anything obstructed, or is your filter making any strange noises? 

The effectiveness of step #4 relies on even distribution of the pH-reducing chemicals in your pool. If your filter isn't working at all, you may want to consult a pool service professional before adding pH reducer.

4. Add pH Reducer to Your Pool

Evenly distribute sodium bisulfate, a popular pH reducer, around the edges of your pool. Read the instructions carefully to ensure you use the correct amount and put it in the pool as directed. In most cases, you need to simply let it dissolve for 15 to 20 minutes. 

A general guideline is to add 30 ounces of sodium bisulfate per 10,000 gallons of water. Most swimming pools are between 15,000 and 20,000 plus gallons, so you may need at least a few pounds of pH reducer to get the job done initially.

Wear gloves, goggles, and other safety equipment when handling sodium bisulfate or any other pH reducer, and keep out of the reach of children and pets. 

Lowering pool pH is possible using muriatic acid. Muriatic acid needs to be handled with caution, as it's a powerful corrosive that could plummet your pool's pH if you add too much. 

5. Retest

Most products ask that you wait four hours to retest, but 12 to 24 hours is probably better for the most accurate reading. If the reading is within range, retest again in a few days to see where the level is.

If it isn't in range, wait at least three days before adding more pH reducer. Gradually changing the levels over time is preferable so you don't wind up overdoing it and then need to treat your pool for having too low of a pH, which comes with its own sets of issues.

How to Prevent High pH in Pools

The number one problem that causes high pool pH is adding too much pool shock. Pool shock is used to raise free chlorine levels in the pool by increasing the effectiveness of chlorine already in the water. Although pool shock is a part of regular pool maintenance, calcium hydrochlorite, its main ingredient, has a pH of 12, which can easily upset the balance.

Check levels on a weekly basis and make minor adjustments as necessary until you get your pH in range. You’ll also want to keep your pool clean to help prevent high ph levels.

DIY vs. Hire a Pro

Most homeowners shouldn't have a problem lowering the pH of their pool by themselves, as a quick trip to the pool store to pick up a pH reducer and possibly a testing kit is all you need to do.

However, if your pool is in serious need of treatment due to algae issues or corrosion, it's probably a good idea to hire a professional. A pool services pro can help get your pH back on the right track. 

Mariel Loveland contributed to this piece.