Test Methods for the Pool/Spa Service Professional

In this blog, we’ll explore the analytical methods commonly found in water test kits—color-matching, drop tests, and electronic—so you can choose the best one for your needs.

VISUAL METHOD

Match a Color: Color-comparison tests (aka color-matching tests) are dependent on the user’s ability to match the color of the treated test sample to a color standard. In most cases, the test is relatively simple…add an indicator to a water sample and then compare the treated sample to a printed-color standard, or, use a test strip and compare the developed color on the pad to a set of printed-color standards.

Printed-color standards are not all created equal; some are superior to others. Here’s what sets them apart:

• how close the printing comes to the target color
• whether colors can be achieved consistently from press run to press run
• how the standards hold up under constant use in wet environments

See a Change in Color: Most drop tests are performed by dispensing a standardized reagent from a dropper bottle into a measured volume of treated sample water until a permanent color change in the sample indicates the endpoint of the chemical reaction. The number of drops required to reach the endpoint is then multiplied by a conversion factor to determine the result. Users who have difficulty matching colors, particularly shades of pink, should be able to see the distinct color change with no problem.

Drop count tests

• have a reputation for giving consistent results over time;
• are very economical;
• can be performed quickly even by inexperienced users;
• have a degree of accuracy sufficient for most applications;
• are great for field use because there are few components;
• do not require any calibration; and
• the upkeep is negligible.

ELECTRONIC METHOD

Use a Meter: Portable or handheld meters, such as colorimeters, completely eliminate the subjectivity of visual color matching. This accurate method of testing water is best suited for pools and spas regulated by health departments or for use by service technicians.

Meters offer

• the highest level of accuracy possible in field testing when properly maintained and calibrated regularly
• ease of use
• minimal technique or knowledge of water chemistry required with well-designed meters
• data-logging capabilities
• features to maximize productivity