pH is the abbreviation for ‘power of hydrogen and is an important factor in pool & hot tubs water chemistry. pH is a measurement of how acidic (0) to how alkaline (14) your water is. Substances that aren’t acidic or alkaline are referred to as neutral. Acids will have a pH that is less than 7 and alkalies have a pH that is greater than 7.
The recommended range of pH should be maintained between 7.2 – 7.6. The main reason that you should keep the pH between these values is for the efficiency of chlorine and other sanitizers. At a pH level of 7.5, you get about 45% useful chlorine. If the pH level was allowed to get to 8.0, then you only get 25% out of your chlorine. By keeping your pH in the range, you maximize how effective your chlorine is and how well it does its job. Saving you time and spending less on chlorine.
Besides Chlorine being less effective at a lower pH it can also cause eye and skin irritation. Acidic water not only stings your eyes and nasal passages, but also strips off natural oils making hair brittle, plus leaving your skin dry and itchy. Unfortunately, the same can arise if pH drifts too high, as well as minerals, will come out which can cause murky water, scaling, and mineral deposits left in the water. Low pH can lead to corrosion on your pool and spa equipment. Acidic water can corrode everything from pumps and other mechanical systems to ladders, slides, and diving board supports. Low pH can even corrode the plaster in a gunite pools. Unbalanced pH can damage vinyl liners, with low pH, a vinyl liner can actually grow, creating unsightly wrinkles. If pH gets too high, a vinyl liner will age more rapidly and have to be replaced sooner.
What causes pH to rise
Surprisingly, Algae can raise pH by consuming carbon dioxide, which removes CO from the water. Every type of sanitizer has a pH impact on pool and spa water, this can depend on the sanitizer being used. Dichlor has a relatively neutral pH, as does bromine, so their pH impact is minimal. Non-stabilized chlorines like calcium hypochlorite, sodium hypochlorite (liquid chlorine), and salt chlorine generators all tend to raise the pH of the pool.
What causes pH to Lower
The water you use to fill your pool is itself may have a low pH. Chemicals, if you have added too much pH reducer. Also, some chlorine tablets such as Trichlor have a low pH of around just 2.8. Similarly, shocking the pool water will lower its pH. Rainwater can be acidic, and especially heavy downpours can reduce your pool’s pH. Organics like Leaves, bugs, grass cuttings, etc. will all contribute to lowering the pH. Our body’s sweat leaves bodily oils, saliva, and urine all combine to lower the pool’s pH. That’s why it’s a good idea to check the pH after you’ve had a pool party.
Keeping pH Stable
There is often some confusion about pH and alkalinity when it comes to water chemistry, the misconception is that these are the same thing. Alkalinity is a measure of calcium, magnesium, and other acid-moderating compounds that act as a buffer to pH change. What is important to understand about alkalinity is that it helps stabilize the pH balance, preventing sudden pH changes in your water, thus keeping the pH within a normal range.
How to Increase pH
There is any number of chemical products that you can use to raise the pH of your pool or spa. Usually, they have names like “Increaser”, “Up”, or “Raise”. Whatever you use all these are all based on sodium carbonate – otherwise known as soda ash. Be aware, sodium carbonate isn’t the same thing as sodium bicarbonate, AKA baking soda. Yes, you can use baking soda to raise the pH in a pool or spa, but it will also affect your alkalinity. You would be more likely to use baking soda in a spa to raise pH and alkalinity at the same time because it is a much smaller body of water. These chemicals can be broadcast over the water near any water return or jet.
How to Lower pH
There are two ways to lower the pH in Pools and Spas. One is Sodium bisulfate it usually comes in powder form. Avoid using it on a windy day to avoid blowback to your skin and clothes. You add this chemical by getting as close to the water as you can and downwind, wind. Wait at least six hours before retesting to make sure your level is correct. Muriatic (Pools Only!) can also be used, this acid is a powerful corrosive so make sure you’re wearing protective gear, such as gloves and goggles. Read the instructions and measure the amount accordingly. Retest the water after six hours.
Pool pH is Always High
The most common reason for a consistently high pH level is using liquid chlorine or a saltwater system as the primary sanitizer. Sodium hydroxide is produced, with a pH of around 13. New pool plaster or pebble finishes will also raise pH in pools, for about a year.
Pool pH is Always Low
The most common cause of consistently low pH levels in pools is using chlorine tablets or stabilized forms of chlorine, which have a pH level of around 3. Acidic rainfall and heavy leaf debris, and dirt/mulch can also lower pool pH levels.
Pool pH is Low, Alkalinity is High
High Alkalinity over 120 ppm can cause some resistance to pH change. And, adding pH Increaser can also raise Alkalinity, compounding the problem.
Pool pH is High, Alkalinity is Low
Low Alkalinity under 80 ppm can cause pH to be unstable and erratic. To raise Alkalinity, add Alkalinity Increaser, which will also slightly raise your pool pH level.
Pool pH will not Increase (or Decrease)
If it seems like you keep adding pH Increaser or Decreaser, but it only seems to last a day, or maybe seems to not affect at all. Total Alkalinity levels over 120 ppm may be preventing you from making an effective adjustment. For pools with high alkalinity and high pH levels, add pH Decreaser or another acid, to affect both.
Is it Safe to Swim or Soak in High or Low pH or Alkalinity?
Maybe yes, maybe no. Your pool water pH and alkalinity can affect disinfection by chlorine. Chlorine is very slow to react at high pH levels and can be over 50% inactive at pH levels over 8.2. However, even with high pH, the water could still be sanitary with good levels of free chlorine, and clear water from effective filtration.
Keep on Swimming N Soaking!
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