Muriatic acid is another name for hydrochloric acid. Hydrochloric acid (HCl) is a compound produced under several conditions: when hypochlorous acid (HOCl) is used in an oxidation reaction; after HOCl has completed the process of eliminating organisms; or when chlorine is degraded by sunlight. The amount of acid produced is nearly equal to the amount of hydroxide produced, resulting in a net pH difference of zero.
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What is the role of Hydrochloric Acid in the pool?
Hydrochloric acid, also known as muriatic acid, is used in pools to reduce the pH and total alkalinity when they exceed the recommended levels. Hydrochloric is also produced when hypochlorous acid, formed from chlorine, is consumed or destroyed by sunlight.
How to increase Muriatic Acid in the pool?
To increase the amount of muriatic acid in the pool, the acid must be added directly to the pool water. The exact amount depends on the current pH and alkalinity levels of the pool. For example, if the pH is between 8.0 – 8.4, then 18 fluid ounces of muriatic acid per 10,000 gallons of water is added. The acid must be added near a return line to ensure optimal mixing. Furthermore, the pump must be running for 24 hours after the addition of the acid.
What are the safety measures when using Muriatic Acid in pools?
When using muriatic acid in pools, it is mandatory to wear recommended personal protective equipment such as goggles, safety glasses, and rubber gloves. The acid must be diluted at a ratio of at least 5:1, preferably 10:1, before adding it to the pool. When diluting, always add acid to water, never water to acid. Large quantities of acid must be added to the pool gradually and cautiously to avoid damaging the plaster. The acid is poured over a return flow while the pump is running, then brushing is necessary to ensure thorough mixing.
How should Muriatic Acid be added to the pool?
Muriatic acid must be added to the pool carefully and in a diluted form. Before adding, muriatic acid must be diluted at a ratio of at least 5:1, preferably 10:1. When diluting, the acid must be added to water, not the water to acid. When adding large quantities of acid to the pool, it must be poured slowly over a return flow while the pump is running, then brushed to ensure thorough mixing. This action prevents the pH from getting too low in one spot, therefore avoiding potential damage to the plaster. Personal protective equipment, such as goggles, safety glasses, and rubber gloves, must be worn when handling the acid.
What is the procedure for using Muriatic Acid in pools?
The procedure for using muriatic acid in pools involves several steps. First, the water must be tested for metals and the following conditions must be ensured: total alkalinity is less than 140 ppm, hardness is less than 350 ppm, and pH is less than 7.4. Adjust if necessary. Then, the pump is turned on and kept running for the next 24 hours. Half of the muriatic acid must be added. This is done near a return line to ensure optimal mixing. Wait for about 20-30 minutes. The remaining muriatic acid is added in the same manner as before. Wait for 2 hours. The pH of the water is tested afterwards. If the pH is very high, 1 quart of muriatic acid is added. If the pH is slightly high add half a quart (1 pint) of muriatic acid. Wait for 2 hours. Test the pH again. Continue testing and adding 1 pint of acid each time until the pH arrives at 7.4.
How to calculate the amount of Muriatic Acid needed for pools?
To calculate the amount of muriatic acid needed for pools, these values are considered: the current pH level, the desired pH level, and the volume of the pool. For example, to lower the pH level from 8.0 to 7.5 in a 16,800-gallon pool, approximately 21 fl. oz. of muriatic acid is required. The required amount of muriatic acid is calculated by multiplying the initial amount needed (in this case, 21.0 fl. oz.) by a volume factor. For a 16,800-gallon pool, the volume factor is 1.68. Therefore, the total amount of muriatic acid required would be 35.28 fl. oz.
For a more specific calculation, such as adjusting alkalinity, the following formula is used: (Current Alk – Desired Alk) / 10 * (Pool Volume / 10,000) * 25.6 fl oz = Acid Dose. For example, for a pool with 15,000 gallons of water, a current pH of 7.8, a current alkalinity of 180 ppm, a desired alkalinity of 100 ppm, and a CYA of 30 ppm, the addition of 2.4 gallons of muriatic acid to the pool is required.
How to Calculate the Required Dose of Muriatic Acid?
To calculate the required dose of muriatic acid, this formula is used: for every 2 oz of borax used, 1.0 fl oz of muriatic acid is needed. This equates to approximately 2.8 gallons of muriatic acid for every 10 boxes of borax. Consider an example where 973.5 oz of borax is utilized. The required amount of muriatic acid is determined by dividing the quantity of borax by the ratio of borax to muriatic acid, which stands at 2.12 oz of borax for every 1 fl oz of muriatic acid. This calculation yields 459.2 fl oz of muriatic acid. To convert this quantity into gallons, 459.2 fl oz is divided by the number of fluid ounces in a gallon, which is 128 fl oz. The resulting quantity is approximately 3.59 gallons of muriatic acid. For 13 boxes of borax, the quantity is divided by 10 and the result is multiplied by 2.8. This calculation yields approximately 3.7 gallons.
What is the Procedure for Using Muriatic Acid and Borax?
- Test the water for metals. If metals are present, their removal or the use of a stain inhibitor is necessary before proceeding.
- Ensure the following conditions: Total alkalinity must be less than 140 ppm, hardness must be less than 350 ppm, and pH must be less than 7.4. Adjustments are made if necessary.
- Activate the pump and keep it running for the next 24 hours.
- Pour approximately half of a borax dose into a large bucket or container and break up any lumps with a scoop or other tool. In this example, 6 or 7 boxes are used.
- Broadcast the powder into the water while walking around the pool using a scoop or plastic bowl.
- Dissolve any accumulated powder on the pool bottom using a pool brush.
- Add half of the muriatic acid near a return line to ensure good mixing. In this example, 2 gallons are added.
- Wait for about 20-30 minutes.
- Add the remaining borax in the same manner as before. In this example, 6 or 7 boxes are added.
- Add the remaining muriatic acid as before. In this example, 2 gallons are added.
- Wait for 2 hours.
- Test the pH of the water. If the pH is very high (for example, above 7.8, often indicated by a purple color on the test), 1 quart of muriatic acid must be added.
- If the pH is slightly high (for example, between 7.4 and 7.8, often indicated by a light to dark red color on the test), half a quart (1 pint) of muriatic acid must be added.
- Wait for 2 hours.
- Test the pH again. The process of testing and adding 1 pint of acid each time is continued until the pH reaches 7.4.
What are the effects of high Cyanuric Acid levels in pools?
High levels of cyanuric acid in pools potentially decrease chlorine’s disinfection rate and require higher levels of free chlorine for disinfection and oxidation. This situation increases the chance of slower disinfection rates and potentially allows for the growth of algae despite regular chlorine treatment. High cyanuric acid levels are not considered a health hazard, but they influence the balance of chemicals in the pool and potentially require draining and refilling the pool to reduce the cyanuric acid level.
Does Muriatic Acid lower alkalinity?
Yes, muriatic acid lowers alkalinity. Muriatic acid is often used to lower the total alkalinity in pool water. The amount of muriatic acid needed is calculated using specific formulas. For example, to lower the total alkalinity by 10 ppm in 10,000 gallons, 25.6 fl oz of muriatic acid is added. The desired change in alkalinity is calculated by subtracting the desired alkalinity from the existing alkalinity. This change is then divided by 10 ppm, the pool volume in gallons is divided by 10,000, and the result is multiplied by 25.6 fl oz. This calculation-based method allows for precise adjustments of pool alkalinity.
How to Lower Total Alkalinity with Muriatic Acid?
To lower total alkalinity with muriatic acid, the following formulas are applied: divide by 125,000 and multiply by the change in ppm, or divide by 500,000 and multiply by the change in ppm. For example, if the pool contains 15,000 gallons of water, has a current pH of 7.8, an existing alkalinity of 180 ppm, a desired alkalinity of 100 ppm, and a CYA of 30 ppm, calculate (180 – 100) / 10 * (15,000 / 10,000) * 25.6 fl oz = 307.2 fl oz or 2.4 gallons. So, it is needed the addition of 2.4 gallons of muriatic acid to the pool to lower the alkalinity by 80 ppm.
Does Muriatic Acid Lower pH Levels?
Yes, muriatic acid lowers pH levels. Muriatic acid, also known as hydrochloric acid, is used to lower the pH and total alkalinity in water. The amount of muriatic acid required depends on the desired decrease in pH level. For instance, to lower the pH from 8.0 to 7.5, 21 fl. oz. of muriatic acid is needed. Acidic pool chemicals like muriatic acid lower pH, while basic pool chemicals like soda ash and sodium bicarbonate raise pH. The rate and ease of pH change vary and are determined by the total alkalinity.
How much Muriatic Acid is required to lower pH by 0.1 at different levels of Total Alkalinity (TA) and Cyanuric Acid (CYA)?
The amount of muriatic acid required to lower pH by 0.1 fluctuates based on different levels of total alkalinity (TA) and cyanuric acid (CYA). When the pH is 7.1, TA is 100 ppm, and CYA is 0 ppm, 8.7 fl oz of acid is needed. If CYA is 30 ppm, 9.18 fl oz of acid is required. When CYA is 50 ppm, 9.82 fl oz of acid is needed. If CYA is 100 ppm, 11.45 fl oz of acid is required.
These quantities are based on a chart that displays the amount of muriatic acid needed to decrease the pH by 0.1 when TA is 100 ppm and CYA is at 0, 30, 50, and 100 ppm. The amount of acid needed increases as the level of CYA increases. For example, when CYA is 30 ppm, 35 times more acid is needed than when there is no CYA and no alkalinity, and 5% more acid than when TA is 100 ppm and CYA is 0 ppm. Similarly, when CYA is 50 ppm, 38 times more acid is needed than when there is no CYA and no alkalinity, and 13% more acid than when TA is 100 ppm and CYA is 0 ppm. When CYA is 100 ppm, 44 times more acid is needed than when there is no CYA and no alkalinity, and 32% more acid than when TA is 100 ppm and CYA is 0 ppm.
How to Adjust pH and Total Alkalinity (TA) in a 10,000 Gallon Pool with Muriatic Acid?
To adjust pH and total alkalinity (TA) in a 10,000-gallon pool, the pH-Total Alkalinity Adjusting Chart must be followed. This chart provides the amount of muriatic acid needed and the subsequent aeration required for different pH and TA levels. For example, if the pH is between 6.5 and 8.5 and the TA is 320 ppm, 588 fl oz of muriatic acid is added and then the pool is aerated. The amount of muriatic acid increases as the total alkalinity increases. After adding the muriatic acid, aeration is necessary to support the distribution of the acid and to adjust the pH and TA levels.
| pH | Total Alkalinity (ppm) | Muriatic Acid (fl oz) | Action |
| 6.5 – 8.5 | 320 | 588 | Aerate |
| 6.5 – 8.5 | 340 | 639 | Aerate |
| 6.5 – 8.5 | 360 | 690 | Aerate |
| 6.5 – 8.5 | 380 | 741 | Aerate |
| 6.5 – 8.5 | 400 | 792 | Aerate |
How does Muriatic Acid impact pool water balance?
Muriatic acid impacts pool water balance by reducing pH and total alkalinity in water. Muriatic acid is the most commonly used substance for this purpose. When added to a pool, it lowers the pH from a higher level to a more desirable level. For instance, adding 35.28 fluid ounces of muriatic acid to a 16,800-gallon pool lower the pH from 8.0 to 7.5. However, it is important to note that concentrated muriatic acid severely damages certain types of pools and must be diluted before adding. It is also crucial to wear recommended personal protective equipment when handling this chemical.
