When the alkaline level of hot water in the bath is too high, the pH content of the water will increase, and the condition of the water will deteriorate significantly. Also, the total alkalinity of the water will probably be high at this point. To lower the pH level in the hot tub, you need to add a pool acid that can lower the pH level and total alkalinity.
Step
Method 1 of 2: Testing the Water
Step 1. Understand the relationship between pH and total alkalinity
The pH level is basically a measure of the acidity level in water. Total alkalinity is a measure of the ability of water to buffer and withstand changes in pH.
- More precisely, pH is a measure of the concentration of hydrogen ions contained in water. The low hydrogen ion content will cause the pH to increase.
- The ability of total alkalinity to measure water resistance is more accurately referred to as a "buffer capacity" measurement.
- When the alkalinity of the water increases or decreases, the pH levels will immediately follow.
- Because the two are so closely related, you often have to adjust them both at the same time.
Step 2. Know the signs of high alkalinity and pH
In general, you can notice the high alkalinity and pH of a hot tub based on the water it is loaded with.
- When the alkalinity and pH are too high, chlorine-based disinfectants will be less effective. As a result, the water quality will deteriorate, causing build-up of stains and other problems in the tub.
- Signs of high alkalinity include scale formation on the sides and bottom of the tub, cloudy water, skin irritation, eye irritation, and poor hygiene conditions.
- Signs of a high pH are also similar, including poor hygiene conditions, cloudy water, scale formation, irritation of the skin and eyes. The durability of the bath filter will also decrease.
- Remember, if you see corrosion, scratched or stained plaster, then the pH and alkalinity levels are likely too low. Rapid changes in pH are also often a symptom of low alkalinity.
Step 3. Test the total alkalinity of the hot tub
If you suspect that the alkalinity of the bath is high, then you should confirm your suspicions by testing the water using an alkalinity test kit or strip.
- The ideal alkalinity range is between 80 and 120 ppm.
- The total alkalinity must be tested before you test the pH.
Step 4. Test the pH of the bath
It's the same with alkalinity, even if you suspect a high pH level in your water, you should measure the actual pH level by testing the water using a pH test kit or strip.
- The ideal pH level is between 7.4 and 7.6, but a decent range is somewhere between 7.2 and 7.8.
- If the pH level of the water is above the ideal range, it means the water is too alkaline or alkaline.
Method 2 of 2: Lowering the pH Level
Step 1. Choose the right chemical
To lower the alkalinity and pH levels, you need to add acid. Liquid muriatic acid (diluted hydrochloric acid to 20 percent) and dry sodium bisulfate are among the most popular choices.
- The acid will combine with water, increasing the hydrogen ion concentration and lowering the pH level.
- Similar to alkalinity, the acid will react with the bicarbonate in the water and lower the total alkalinity in this process.
- You can also look for "pH lowering," "alkaline-lowering," or "combination-lowering" chemicals that are commonly available at pool supply stores.
Step 2. Determine the initial measurement based on the total alkalinity
The pH level will decrease faster than the alkalinity, so you will need to adjust the alkalinity of the water first. When you balance the alkalinity, the pH level will adjust gradually.
- Always follow the instructions on the pH/alkalinity chemical when you prepare the right amount.
- As a general rule, you need 725.75 grams of sodium bisulfate or 1.23 L of muriatic acid for every 37.85 kL of water to lower total alkalinity by 10 ppm.
Step 3. Mix the chemical with a little water
Fill a 30.28 L plastic bucket to 3/4 full with tub water. Pour all the pH lowering liquid into the water and let it dissolve.
You have to put the acid in the water. Pouring acid into the bucket before first filling it with water can cause damage to the bucket and ineffective mixing
Step 4. Turn on the hot tub
Make sure that the pump and filter are working. The hot tub should be set to the usual temperature and speed before you move on to the next step.
It's also important, you have to make sure that no one is in the tub when you adjust the water conditions
Step 5. Add the diluted chemical to the hot water bath
Slowly pour the diluted pH reducer into the center of the tub.
Pour the acid gradually, not all at once. Pouring acid too quickly can damage the sides, base, and equipment of the hot tub
Step 6. Let the water adjust to its conditions
Use a pump to circulate the water for three to six hours after you add the pH reducer.
During this time, the pump will circulate the water and acid together more thoroughly. The pH and alkalinity levels of the water in the tub will become consistent when the water and acid are properly mixed, and you will need to wait for the measurement levels to be consistent before proceeding any further
Step 7. Test the alkalinity and pH levels again
Test the alkalinity first, then test the pH.
- If done correctly, the alkalinity of the water should now be balanced, but it's possible that the pH is still out of balance.
- If the alkalinity or pH level is still high, then repeat the process. Continue as necessary until the water content is quite balanced.
Step 8. Drain the water regularly
You should drain all the water in the hot tub at least every four to six months. After that, refill the tub with water, balance the pH and alkalinity levels as necessary, and continue to monitor water conditions as usual.
- You'll need to balance the pH and alkalinity of your water almost every week if you use the hot tub regularly. Adding chemicals to water too often can cause excessive staining, and you'll find that balancing the water conditions becomes more difficult.
- When you feel that the water conditions are difficult to balance, then it is time to replace the old water with new clean water.
Warning
- Wear gloves when handling any type of pool acid. Never touch acid directly with your hands or other unprotected body parts.
- Also consider wearing eye protection. If you don't, you could splash your eyes with acid when you pour it into the hot tub.
- Be careful when using pool acid. The acid can cause irritation, burns, and temporary/permanent blindness at its worst.
