Alkalinity is another important property of your water. In the previous section about pH, it was noted that the addition of acidic substances (such as rain water or muriatic acid) will lower your water’s pH, and adding basic substances (like “pH Up”) will raise your pH. Alkalinity is a measurement of substances that act like bases – in that they neutralize acids – but without raising pH.
To put it another way, the more Alkaline your water is, the more it will resist a drop in pH. If your Alkalinity is low, your pH will be less stable and more difficult to control. However, too much Alkalinity can cause scaling and other problems.
The best way to raise Alkalinity is to add baking soda to your water. It seems odd to add a cooking ingredient to your pool water, but baking soda (NOT baking powder) is one of those substances that acts like a base and neutralizes acids without raising your pH.
As with other adjustments, use the tool at www.poolcalculator.com to determine the amount of baking soda to add. Like adjusting stabilizer, it’s best to add a less than the suggested amount first and then measure again so that you don’t overshoot your target.
This tactic is especially important with Alkaliity because Alkalinity takes time to lower. First, you must aerate (add air to) the water. There are many ways to do this, fountains, water toys, some pool vacuums, air compressors, aquarium equipment, or even just having a bunch of neighborhood kids splash in your pool. The idea is to create lots and lots of bubbles in the water. This will lower your alkalinity and raise your pH. The next step is to bring the pH back down. Then you simply repeat the process until alkalinity has been reduced to the desired level.