Last night we received an inquiry from ‘Kara-Lynn’ who asked, “Why do your test strips have tests for ph and alkalinity? Both have to do with acids-bases so aren’t they the same thing?”
Thanks, ‘Kara-Lynn’, for this very good question about the relationship between pH readings and alkalinity readings when testing water. A good many people have confusion on this topic!
Going back in time a bit…
Many years ago when we worked in a pool store that performed free water testing and (obviously) also sold a variety of pool water adjustment chemicals that raised the pH, lowered the pH, raised the alkalinity, or lowered the alkalinity levels of pool water we faced customers on a regular basis that had questions about the relationship between pH and alkalinity.
Quickly we learned a very simple way to explain the relationship:
- Think of alkalinity as a total number of particles that can change color in a body of water.
- Think of pH as the range of colors that each particle could change.
- If color change is required: It is easier to convince a small number of the color-changing particles to change color than it is to convince a large number of color-changing particles.
- If color change is unwanted: It takes more effort to convince a large number of color-changing particles to change color than it does to convince a small number of color-changing particles.
- Higher alkalinity means greater color (pH) stability. Lower alkalinity means less color (pH) stability.
Some people understood the meaning of my little story asked for more information on how they could test for both parameters since a clear relationship existed between pH and alkalinity.
For those folks we suggested pool water test strips like the Pool Check 5-Way and the Pool Check 6-Way test strip products as the easiest ways to keep tabs on both the pH and alkalinity of pool water.
Other people developed a blank look on their faces and simply said, “Yeah, OK, just tell me what I need to buy”… and went on their merry way.
Testing pH & alkalinity in drinking water
Can you use pool & spa test strips to test the pH and alkalinity of drinking water? Yes, but in general the manufacturers of pool & spa test strips calibrated those products using water with a higher temperature.
Therefore, we suggest using products specifically designed to test water with a cooler temperature such as the WaterWorks pH & Total Alkalinity Test Strips which come packaged in bottles of 50 tests for each parameter and cost less than $10 per bottle.
Detection ranges for the WaterWorks pH & Total Alkalinity Test Strips:
- pH: 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0
- Total Alkalinity: 0, 80, 120, 180, 240, 360 ppm (mg/L)