Maintaining a backyard swimming pool is a great way to cool off during hot summer days. However, keeping the water clean and safe requires some basic knowledge of water chemistry. One common issue that pool owners face is low pH. When your pool water becomes too acidic, it causes problems for both the swimmers and the pool equipment itself.
A healthy pool relies on balanced water. If your pool has low pH, you need to find the cause and fix it quickly. This guide will explain what low pH means, why it happens, and the exact steps you can take to bring your pool water back to a safe level.
Understanding Pool pH Levels
The term pH stands for potential of hydrogen. It is a scale that measures how acidic or basic a liquid is. The scale runs from 0 to 14. A rating of 7 is completely neutral. Anything below 7 is acidic, and anything above 7 is basic or alkaline.
For a swimming pool, the ideal pH level is between 7.4 and 7.6. This specific range is perfect for a few reasons. First, human eyes and skin have a pH of about 7.4. Keeping your pool water in this range prevents eye irritation and itchy skin. Second, your pool chlorine works best at this level to destroy bacteria and algae.
When your pool water drops below 7.2, it is officially considered low pH. If it falls below 7.0, the water becomes highly acidic.
Top Causes of Low pH in a Swimming Pool
Pool water does not just change on its own. Specific outside elements lower the pH level over time. Here are the most common reasons your pool water is too acidic:
1. Heavy Rainfall: Rainwater is naturally acidic. As rain falls through the air, it mixes with carbon dioxide and other gases. When a major rainstorm hits your area, a large amount of acidic water enters your pool. This dilutes your pool chemicals and lowers the overall pH level.
2. High Swimmer Usage: Human bodies affect pool chemistry. Sweat, body oils, saliva, and urine are all naturally acidic. When many people swim in the pool at the same time, they leave these substances behind. A busy weekend pool party can easily push your pH down.
3. Overuse of Chlorine Tablets: Most pool owners use trichlor chlorine tablets to keep their water clean. These tablets are very convenient, but they have a very low pH of about 2.8. As these tablets dissolve in your pool skimmer or chlorinator, they constantly add acid to the water. Over time, this slow drop causes a noticeable low pH issue.
4. Environmental Debris: Leaves, twigs, grass clippings, and bugs frequently blow into outdoor pools. As this organic matter sits in the water, it begins to rot. The decomposition process releases natural acids directly into your pool water, which drops the pH level.
5. Low Total Alkalinity: Total alkalinity acts as a protective shield for your pH level. It absorbs sudden chemical changes to keep the pH stable. If your total alkalinity drops below 80 parts per million (ppm), your pH level will bounce up and down easily. Low alkalinity allows the pH to crash down without anything stopping it.
The Hidden Dangers of Acidic Pool Water
Ignoring low pH can lead to expensive repairs and uncomfortable swimming conditions. Acidic water is aggressive and damages almost everything it touches.
- Damage to Pool Equipment: Acidic water eats away at metal parts. It will slowly corrode your pool pump, ladder, lights, and the heat exchanger inside your pool heater. This metal corrosion can ruin your equipment, leading to costly replacements.
- Plaster and Vinyl Ruin: If you have a concrete or plaster pool, low pH water dissolves the minerals right out of the surface. This creates a rough texture that catches algae and scrapes your feet. For vinyl liner pools, high acid levels cause the plastic to become brittle, leading to wrinkles and cracks.
- Skin and Eye Irritation: Have you ever left a pool with burning red eyes and dry, itchy skin? Low pH is usually the culprit. Acidic water strips away the natural protective oils on your skin and irritates sensitive eye membranes.
- Stained Pool Surfaces: As acidic water corrodes the metal parts in your pump and plumbing, those metals dissolve into the water. When the metals settle out, they leave dark brown, black, or purple stains on your pool floor and walls.
How to Test Your Pool Water
You cannot determine your pool’s pH level simply by looking at the water. Even clear water can be highly acidic. You must test the water using a reliable home test kit or digital testing strips.
- Collect a Water Sample: Reach your arm about one foot down into the pool to collect the water sample. Do not take water from the very surface, as sun and air can change the readings. Take the sample away from the return jets.
- Use Test Strips or Liquid Kits: Dip a test strip into the sample for a few seconds, or add the specified number of indicator drops to your liquid test block.
- Compare the Colours: Match the colour of the water or strip to the chart provided with your kit. Look for the pH reading and write it down.
Always check your total alkalinity level at the same time, because you cannot fix your pH permanently without fixing the alkalinity first.
Step-by-Step Guide to Fixing Low pH
Once you know your pool has low pH, you can fix it using common pool chemicals. The two primary products used to raise pH are sodium carbonate (commonly called soda ash) and sodium bicarbonate (baking soda).
- Test and Calculate: Test your pool water to find the exact pH and total alkalinity numbers. Read the instructions on your soda ash package to calculate how much chemical you need based on your pool’s total volume in gallons.
- Pre-Dissolve the Chemical: Fill a clean five-gallon bucket with pool water. Slowly pour the measured amount of soda ash into the bucket. Stir the mixture with a plastic stick until the white powder dissolves completely. Never add water to dry chemicals; always add dry chemicals to water.
- Pour into the Pool: Turn on your pool pump to get the water moving. Walk around the deep end of the pool and slowly pour the dissolved mixture directly into the water. Avoid pouring it directly into the skimmer box.
- Let the Water Circulate: Keep your pool pump running continuously for at least one to two hours. This ensures the chemical spreads evenly throughout the entire pool.
- Retest the Water: After two hours of circulation, take a new water sample and test the pH again. If the level is still below 7.4, repeat the process with a smaller dose of soda ash.
Choosing the Right Chemical: Soda Ash vs. Baking Soda
Many pool owners confuse soda ash with baking soda because they have similar names. However, they do different jobs in your pool.
- Soda Ash (Sodium Carbonate): This chemical has a very high pH level. It raises your pool pH quickly while only causing a small rise in total alkalinity. Use this if your alkalinity is fine but your pH is low.
- Baking Soda (Sodium Bicarbonate): This chemical is great for raising total alkalinity. It will only cause a very slight increase in your pH level. Use this if both your pH and alkalinity are low.
| Chemical Name | Everyday Name | Primary Use | Impact on pH | Impact on Alkalinity |
|---|---|---|---|---|
| Sodium Carbonate | Soda Ash | Raises low pH | High | Low to Medium |
| Sodium Bicarbonate | Baking Soda | Raises Alkalinity | Low | High |
How to Prevent Low pH Issues
The best way to manage low pH is to prevent it from happening in the first place. Consistent maintenance habits will save you time and money on pool chemicals.
- Run Tests Weekly: Test your pool water at least once a week during the swim season. Catching a small drop early is much easier than fixing a severe chemical imbalance later.
- Skim Debris Daily: Remove leaves, bugs, and organic material from the surface before they sink to the bottom and rot. Clean out your skimmer baskets regularly.
- Use a Pool Cover: Put a cover over your pool before heavy rainstorms. This keeps acidic rainwater and windblown debris out of your clean water.
- Monitor Alkalinity: Keep your total alkalinity between 80 and 120 ppm. This acts as a buffer to keep your pH stable all year long.
Conclusion
Keeping your pool water balanced can feel like a balancing act, but handling low pH does not have to be stressful. When you know what causes the drop like heavy rain or constant chlorine use you can catch the issue early. Regularly testing your water and keeping a close eye on your total alkalinity are your best defences against acidic water. By taking these simple steps, you will protect your expensive pool equipment, prevent ugly stains, and keep the water completely safe and comfortable for your family all summer long.
If you are struggling to keep your chemical levels steady, or if you want an expert to handle the hard work for you, we are here to help. Contact us at Gator Pool Services today to schedule a professional water balancing or set up a regular pool maintenance plan.