Are you wondering why the pH keeps rising in your saltwater pool? Saltwater swimming pools use chlorine generators to produce chlorine, which is released automatically into the pool to maintain the recommended (free chlorine) FC levels.
A chlorine generator uses salt (Sodium Chloride) and water during the process known as electrolysis, where the two main byproducts are Chlorine and Sodium Hydroxide.
The byproduct Sodium Hydroxide has a very high pH level and will increase the pH level in your water.
It becomes much worse when your free chlorine production level is too high because, for every chlorine produced, there is an equal measure of Sodium Hydroxide.
As such, the first sign that you have more sodium hydroxide (pH increaser) is when the free chlorine level (FCL) in your pool water is too high than the recommended level of 3 ppm - 5 ppm.
Another indicator that your pool is full of sodium hydroxide might be a high level of Cyanuric acid (Cya) or chlorine stabilizer, which in turn will make your chlorine generator produce more chlorine (and sodium hydroxide) to much the strength of the stabilizer and be effective in sanitizing the water.
Another common reason your pH level will rise unusually quickly is when the total alkalinity (TA) level is too high in your pool water, whether saltwater or non-saltwater. As such, always ensure your TA level is between 80-120ppm for a saltwater pool.
In short, we have learned that pH rises uncontrollably in saltwater pools due to:-
1) Rise in TA and
2) A high chlorine production level produces a higher pH-concentrated sodium hydroxide solution.
The only two ways to permanently control the pH level in a saltwater pool are to control the chlorine production level and to lower the TA level. Before you start working on fixing your pool's pH, you must know what is causing the unusual rise in the pH.
Note that you can use a strong acid like muriatic acid to lower the pH level in your water.
However, if high chlorine production is the cause, pH will reduce for a short while when the acid is added. But will shoot back up as more sodium hydroxide will be produced during chlorine production.
How To Control the Chlorine Production Level in Saltwater Pools
Chlorine production levels in saltwater pools can be controlled in the chlorine generator settings.
Turn down the percentage settings in your saltwater chlorine generator to the lower settings to slow chlorine production.
If the FCL is too high, reduce your pump's run time also to lower it faster.
Also, ensure that your Cya levels are within the recommended range of 70 ppm to 80 ppm for a saltwater pool.
The most recommended way to lower your stabilizer level is by draining and refilling some pool water with a fresh one, then balancing all pool chemicals, starting with the pH and Chlorine in that order.
Once you keep the chlorine production level under control, trust me, your pH level will also be under control. For more, visit how to fix free chlorine problems in a saltwater pool.
How To Control the Rising pH Caused by High TA Level
When the pH rise is not caused by a high chlorine production level releasing more sodium hydroxide into the pool or a high stabilizer level in your water, then your TA is the cause.