Measuring pH

Tools and techniques for the lab and field

Comparison of Methods

Test Strips (Litmus)

Most affordable and portable. Paper is infused with indicators that change color. Accuracy is typically +/- 1 unit.

Liquid Test Kits

Common in pool and aquarium care. You add drops of a reagent to a sample. Provides better accuracy than strips (often 0.2 to 0.5 units).

Digital pH Meters

Scientific standard. Uses a glass electrode to measure electrical potential. Requires calibration but offers precision down to 0.01 units.

Calibration Tips

Temperature Matters: pH changes with temperature. Meters with ATC (Automatic Temperature Compensation) are best.
Buffer Solutions: Always calibrate using known buffer solutions (usually 4.0, 7.0, and 10.0).
Storage: Never let a digital probe dry out. Use specialized storage solution (KCl).

300x250 Medium Rectangle

Best Practices

Sampling & Dilution

Rinse your testing container with the sample water twice before taking the actual measurement. Remember that adding tap water to an acidic sample for "volume" will result in dilution, shifting the reading toward neutral.

Reading Color

When using color-based tests, always read the result under natural daylight. Artificial indoor lighting can significantly skew your perception of the color match.