A common additive in swimming pools, muriatic acid is essential in ensuring that a proper pH balance and alkalinity are maintained in the water. With increasing pH and alkalinity levels, muriatic acid counteracts this and will restore these levels to an acceptable range.
Adding too much muriatic acid, however, may result in excessively low pH levels and alkalinity levels. This can lead to eye irritation and skin rashes, as well as damaging metal and plastic elements of the pool.
For this reason, swimming pool owners should be aware of what to do when too much muriatic acid is added to the pool.
Dangers of Adding Too Much Muriatic Acid
Adding an excess of muriatic acid can have significant consequences, both for the pool equipment and any swimmers.
Here’s what happens when you add too much muriatic acid:
- Low pH
- Low total alkalinity
- Etching of concrete and other surfaces
- Rusting of metal fittings (nuts, railings, ladders, etc.)
- Vinyl liners become brittle
- Plastic components weaken and become brittle
Beyond the damage to the pool, rashes and skin irritation in swimmers is another danger posed by too much muriatic acid and low pH.
The damage to a pool is typically not a problem if you, relatively quickly, correct the low pH levels associated with too much muriatic acid. If you were to leave your pool with low pH for days, weeks, or months, you run into serious problems.
Related Reading: Low PH in Pool: How to Raise
How Do You Know if You’ve Added Too Much Muriatic Acid?
Maybe you’ve added muriatic acid (aka hydrochloric acid) to your pool but you suspect you’ve added too much. Predicting how much the pH changes when adding acid can be tricky and isn’t always an exact science for the average swimming pool owner.
This may not be the only reason you’ve added too much muriatic acid. Maybe you measured incorrectly or misread the instructions.
If you suspect you have too much muriatic acid in your pool, how can you tell?
The easiest way to check is to:
- Test the alkalinity
- Test the pH
Testing the pool water is traditionally a matter of using a pH test kit. The recommended alkalinity and pH levels should be:
- pH between 7.2 and 7.8 pH
- Alkalinity levels should be in the 80 to 120 parts per million range (ppm).
When testing the water, ensure that you’ve run the pool pump for at least a couple of hours before. This is to make sure the acid has been fully mixed with the pool water.
If you haven’t allowed adequate time for the muriatic acid to mix, it’s possible you could get a high reading when testing the water. Maybe your water sample was from a concentrated patch of water.
Related Reading: How Much Muriatic Acid To Lower Pool pH & Alkalinity
Two Distinct Pool Testing Approaches
There are three ways you can test your alkalinity or pH:
- Test Strips
- DPD Drop Test Kits
- Electronic or Digital pH Testers
DPD Drop Test Kits
The most accurate way to test your pool is with a DPD drop test kit. Most pool professionals use these kits because they are reliable. Many pool owners have been led astray with incorrect test results.
Do yourself a favor and buy a quality test kit like this one:
With many brands available, test strips are typically dipped to elbow depth in the pool and immediately removed. The strip changes color and will correspond to the range specified on a color chart included on the bottle.
One product available on Amazon is a set of 100 Ultimate At Home Pool Test Strips.
Distributed by JNW Direct, this product offers tests for seven parameters, including total chlorine, free chlorine, total hardness, bromine, pH, and total alkalinity.
Electronic Digital pH Tester
Because test strips may occasionally yield inaccurate results, some pool owners prefer an electronic approach. A digital pH water tester will get the job done in this case.
Similar in size to a digital thermometer, this pH Tester offers +/-0.01 pH accuracy with auto-calibration that ensures accuracy across temperatures that range from 32 °F-140 °F (0 °C-60 °C).
Beyond pools, the device has uses that extend to checking the pH of aquariums, hydroponic systems, and spas.
Related Reading: 7 Easy Tips for Accurate Home Pool Water Testing
What to Do if You Add Too Much Muriatic Acid
Now you know that your pH and alkalinity are likely too low after adding the incorrect amount of muriatic acid. How do we fix our pool after adding too much acid?
First don’t panic, we’ll walk you through it step by step. It’s really just a case of restoring the alkalinity and pH levels back to the recommended ranges.
1. Test the pH and alkalinity of the water
First, you need to know what you’re dealing with. As explained earlier, test that water.
2. Choose the Approach
You’re going to use a different approach depending on your test results. As a reminder the ideal levels:
- Total alkalinity: 80-120 ppm
- pH: 7.4-7.6
Alkalinity is correct but pH is low: If the pH is around 7.1 or higher, you’re going to try aerating the pool water. Aerating will raise the pH. You can do this by pointing the return jets up and switching on any water features. If you have a saltwater pool, turn on the salt generator.
Leave the pool overnight and retest the water. If the pH is increasing, continue this method, if not, choose another method below.
If the pH is very low, use Soda Ash to increase the pH instead of relying on aeration.
Alkalinity is low but pH is almost correct: You’ll be using Baking Soda (sodium bicarbonate) to raise the alkalinity. This will mostly increase the alkalinity and only slightly increase the pH. Follow the instructions on the pack for the amount to add.
Run the pump to circulate the water, then test the water a few hours later. Keep adding a little baking soda at a time until you get the correct alkalinity. If the pH is still a little low but the alkalinity is correct, use the aeration method listed above to increase the pH.
Alkalinity and pH are Low: If the alkalinity is very low, use baking soda to increase it to the correct levels. This will also raise the pH but not by much. You can then increase the pH to the correct levels by aerating the water, adding soda ash, or adding borax to the water.
3. Mix the Soda Ash or Baking Soda
If using soda ash or baking soda, fill a 4-5 gallon bucket with water approximately three-fourths full, ensure safety by donning goggles or other eyewear that guards against splashing.
Follow the directions on the pack and carefully measure the required dose.
Add the soda ash or baking soda and dissolve. With the pump running, slowly pour this into the deep end of the pool. Preferably near a return jet.
4. Run Pump for 2-4 Hours
Running the pump will circulate the chemicals you just added throughout the pool. Wait and give enough time for the pool water to completely cycle. Failure to wait long enough could mean you get false test readings.
5. Retest the Water
Retest the pH and alkalinity of the water. If they are not correct, repeat the process. You’re aiming for a pH of 7.4-7.6 and alkalinity of 80-120 ppm.
Tip: You’re better to use half of what you think you need when making alkalinity and pH adjustments. It’s much easier and causes fewer problems if you undershoot rather than overshoot.
How Much Baking Soda to Fix Too Much Muriatic Acid
You may be wondering how much baking soda do you need to fix your pool? The amount will depend on your pH and alkalinity levels. As a basic rule, you can use 1.5 pounds (680 grams) of baking soda for every 10,000 gallons (37,854 liters) of water in your pool.
When adding your baking soda, it’s best to add about half of what you think you need. That way you are unlikely to overshoot. Sometimes it can be hard to calculate the exact amount of baking soda needed with accuracy.
Related Reading: Soda Ash or Baking Soda for Pool | Which is Better?
How Much Soda Ash to Fix too Much Muriatic Acid?
If you wish to increase the pH level in your pool and the alkalinity, 5 ounces (141 grams) of soda ash per 10,000 gallons (37,854 liters) of pool water will raise the pH level by approximately 0.1. It’s best to add this in small amounts. Add no more than 1 pound (453 grams) at a time. Then retest the water after a few hours and add more if necessary.