Digital pH meters vs pH test strips

Criteria

pH Paper test strips

pH digital meter

Accuracy

Less Accurate:

pH test strips only give an approximation of the pH level based on a colour scale

More accurate:

Digital pH meters provide more accurate measurements than pH test strips. A digital pH meter can measure the pH of a solution to within 0.01 pH units

Human error

Very operator dependent:

The interpretation of the colour change can be subjective and influenced by factors such as lighting conditions, colour blindness, and individual differences in perception, leading to inaccurate pH measurements. Additionally, if the colour chart used to interpret the results does not properly match the actual colour of the strip, it can also result in errors (especially in the case of low-quality pH test strips)

Little impacted by human operator:

Little room for human error as the reading is directly showing the pH value.

Precision

Less precise:

the results from pH test strips can be influenced by factors such as humidity and temperature, which can affect the colour of the strip

More precise:

Digital pH meters are more precise than pH test strips. A digital pH meter can give repeatable and consistent measurements

Longevity

Shorter life span:

pH test strips have a “best before date” which causes them to become less accurate over time. This is usually three years from the manufacturing date.

Longer life span:

Digital pH meters are more durable than pH test strips. Digital pH meters can last for years with proper care and regular calibration

Staining effects

Large impact:

Liquids that have a lot of colours can stain the pH test strip, which can obscure the colour change and affect the accuracy of the pH measurement. This can sometimes be experienced by molasses fermentations.

No to little impact:

Very little, if any, impact of staining on readings.

pH Paper test strips

pH digital meter

Pricing

Cheaper:

A single pack of pH test strips usually contains a minimum of 100 strips, which can last for a considerable amount of time, especially for home and hobby distillers.

More expensive:

The price of digital pH meters can vary quite significantly. They are more expensive compared to pH test strips.

Maintenance

Low maintenance:

It requires no maintenance but should be used within its “best before date” for accurate results.

High maintenance:

Requires regular calibration and replacement of batteries.

Size of sample

Small Sample required:

In certain industries, particularly in the medical field, it is preferable to use only a small amount of the sample.

Larger sample required:

You need enough liquid to cover the probe of the pH meter.