7 Habits of Highly Effective Water Analysts
Inaccurate test results are not always the fault of the water-testing equipment or because something in the water’s chemistry is interfering with the test.
Most often, sloppy technique or poor housekeeping is to blame. And that’s good news because you can rectify the situation easily and usually at no expense.
You may think instructions for using a simple test strip are superfluous. What’s that old saying, “When all else fails…read the instructions”?
Well, as a test strip manufacturer, I can tell you there are important differences between brands. That’s because there are different motions designed to expose the reagent pads to the water in a specific way for a specific time. If you use the strip incorrectly, you are going to get unreliable results. This is not the fault of the strip!
Even if it is the same test equipment from the same manufacturer, something important in the procedure may have changed. The takeaway here is that if a “simple” test strip has a required technique for successful use, you can bet the farm all your other testing supplies do too. Stay informed by reviewing the instructions.
2. WATER SAMPLE
Test results are used to make treatment decisions, but if the sample employed for the test is not representative of conditions in the whole pool, your results will be inaccurate, resulting in improper treatment.
How to obtain a good water sample:
- Use a clean sample container.
- Avoid sampling near return lines, chemical feeders, and dead zones (midpoint of the pool is best).
- Take the sample at the specified depth.
Do not allow a water sample to sit for any length of time. The sanitizer residual is particularly apt to change if the sample is allowed to sit, resulting in a false-low reading. If instructed to observe a wait time after adding reagent(s), do not omit this step. Several tests need extra time for proper color development, including multiparameter test strips, so it’s important to read the test results in the order specified.
Note: After adding a treatment chemical, allow at least two filtration cycles to pass before retesting in order for the product to circulate.
4. SAMPLE VOLUME/ADDITION OF REAGENTS
Carefully measure the sample volume and be sure to add the correct amount of reagent. Sometimes even a slight variance in either can have a major impact. Here are some basic rules:
- When using a dropper bottle to dispense reagent, always hold bottle in a vertical position.
- Do not allow static buildup on dropper tip, which reduces size of drops/amount of reagent dispensed.
- Completely incorporate any reagent powders or tablets, being especially vigilant when using square test vials where reagent can get stuck in the corners.
- To avoid improper measurement, remember to check for air bubbles if using a pipet.
5. AMBIENT LIGHT
Most manufacturers recommend doing color-matching tests in natural light (but not looking into the sun) since artificial lighting skews color perception, as will wearing sunglasses. When testing indoors, the use of an inexpensive daylight simulator is recommended. Colorimeter users need to be aware that stray light will interfere with a test, so it’s important to close the sample chamber lid/cap as directed.
Contamination can foul test results. Here are some tips to help avoid contamination:
- Thoroughly rinse sample container, test cells, and caps to remove any residue from a previous test.
- Do not switch caps between reagent bottles or place them on an unclean surface.
- Do not use your finger to cap a test cell when swirling a sample to incorporate reagents or allow your finger to touch the pads on a test strip.
In addition to the tips above, these precautions should be observed when using electronic test instruments:
- Calibrate your meter according to the manufacturer’s recommended schedule.
- Follow instructions for soaking the electrode on tester when it’s in storage.
- Rinse the electrode between measurements with distilled or deionized water to avoid cross-contamination, as well as long-term damage from aggressive solutions.
- When using a digital reader, be sure to lay the test strip down on the reader exactly as directed.
7. PAY ATTENTION
It’s paying close attention to what’s happening during each and every test that’s the real challenge — Zone out, and you lose out!
It’s just as easy to develop a good habit as a bad one. If you see room for improvement in your testing technique or the way you care for your testing supplies, turn over a new leaf today. Your reward…accurate, reliable test results!