Having pH levels that are higher than 7.8 or lower than 7.2 can cause problems for your and you hot tub. High pH is a common cause of calcium and scale build up at your hot tub water line and cloudy or dull water. It also causes bathers to often experience itchy skin and burning eyes.
A pH level of 7 means that water is neutral; above 7 means the water is alkaline, while below 7 indicates acidity. Aim for a pH level of between 7 and 7.6. If the water pH is higher than 8, anyone who swims in the pool is at risk of skin rashes, while a pH of lower than 7 can sting swimmers' eyes.
In order to lower both the pH and alkalinity of your hot tub water, you will need to add acid. Common choices are liquid muriatic acid or dry sodium bisulfate. When the acid is introduced to the water, it increases the hydrogen concentration and lowers the pH.
Hot tubs in particular generate a lot of bubbles and tend to have higher temperatures. This combination creates a gas called carbon dioxide very quickly. Carbon dioxide builds up and makes the pH go up. This is why hot tub owners, on a regular basis, need to add something to lower their pH and alkalinity.
To lower the pH level of your hot tub water, you can take four cups of vinegar and pour it in the water. Remember to circulate the water in the tub before you pour in the vinegar. You can either use the vinegar you have at home or use apple cider vinegar. Turn off the jets and test the water after a few hours.
Shocking the water will also cause a pH spike, as it breaks up combined chlorine (chloramines) while increasing free chlorine. Most homeowners use their main water sources to fill the tub. Depending on where the water comes from, it could have a high pH level to begin with.
Using liquid chlorine raises the pH of the water.
Liquid chlorine does not raise pH. When added to water, liquid chlorine (which has a pH of 13) makes HOCl (hypochlorous acid – the killing form of chlorine) and NaOH (sodium hydroxide), which raises pH.
To bring down pH, use a made-for-pools chemical additive called pH reducer (or pH minus). The main active ingredients in pH reducers are either muriatic acid or sodium bisulfate (also called dry acid). Reducers are readily available at pool supply stores, home improvement centers and online.
After adding pH increaser or decreaser you'll want to wait about two to four hours, although some chemical manufacturers suggest a full turnover cycle, before retesting. The smaller the increments you need to adjust for pH, the less time you'll need to wait for the results to become stable.
Hot tubs are often at a pH level of 7.2 – 7.8. Adding chlorine will increase this number slightly, but because the chemical also reacts to form hypochlorous acid, which reduces acids and makes your hot water less acidic, there's no change unless large amounts of chlorine are added.
High chlorine levels decrease the pH of your pool's water, making it more acidic. The more acidic the water, the higher the likelihood of corrosion. This corrosion can affect metal piping, equipment, and the surface of your pool (tiles, liners, concrete, etc.).
If you wish to lower the pH without also reducing the Total Alkalinity, simply pour the dose of muriatic acid about the pool. “ This would all be wonderful if it was only accurate. Still, just like the mythological “Chlorine Lock,” folkloric tales within the swimming pool industry do persist.
When the PH of water becomes greater than 8.5, water taste can become more bitter. This elevated pH can also lead to calcium and magnesium carbonate building up in your pipes. While this higher pH doesn't pose any health risks, it can cause skin to become dry, itchy and irritated.
Algae raises the pH of water too
Algae consume carbon dioxide, which removes it from solution. In effect, this consumption of CO2 raises the pH, and enough algae can raise the pH of your swimming pool well above 8.2.
Adjusting pH in Water
Pure or distilled water has a pH level of 7, which means it is neutral. If you want to increase the pH of water, you must add an alkaline substance, such as baking powder, to it. If you want to decrease the pH of water, you add an acidic substance, such as lemon juice, to it.
When you've determined that your pool pH is too high, there are two ways you can balance it: dry acid or muriatic acid. If you're using a dry acid, use these steps: Follow the manufacturer's instructions on the package. Use the recommended amount only.
Alkalinity Balance, pH up, pH down, Calcium Balance, Water Stabilizer, and clarifier are all swim-safe chemicals. Wait about 20 minutes, and you are free to swim.
Ordinary household vinegar could in theory be used to lower the pH of your pool. The pH of vinegar is about 2.5, which is quite acidic when compared to your pool water. Household vinegar is very weak though (when compared to a strong acid like muriatic acid), so you would need quite a bit to lower pH.
How do I lower the pH in my water naturally? A simple way to lower the pH in your water naturally is to use lemon juice. Simply drop 2-3 drops of lemon juice to an 8 fl oz (240 mL) glass of water. The acidity of a lemon naturally lowers the pH level of the glass of water.
Can You Safely Swim in a Pool With High Alkalinity? As long as you have enough chlorine in your pool (around 3ppm for total chlorine) and the pH level is balanced (between 7.4 to 7.8), then a pool with high total alkalinity is still safe to swim in.
Swimming pool pH reducer is made of granular sodium bisulfate and will act quickly to correct your pool's pH level to re-establish an ideal swimming environment. pH reducer can be used to lower swimming pool pH levels whenever they rise above 7.6 ppm.
If theres too much chlorine it will vaporise and form gas that floats just above the surface of the water. If this vapor is inhaled it can inflame airways and exacerbate certain breathing conditions. Read more What Temperature Should My Spa Pool be at and Why?
If the chlorine levels are too high, you can either wait it out and let the chlorine break down naturally or replace some of the water in your hot tub with fresh water. You can also use a chlorine neutralizer to quickly eliminate excess chlorine.
Baking soda, also known as sodium bicarbonate is naturally alkaline, with a pH of 8. When you add baking soda to your pool water, you will raise both the pH and the alkalinity, improving stability and clarity.