Testing equipment should be kept clean, with no water marks, fingerprints, scratches or stains and preferably, rinsed with distilled water where applicable. Note that plasticware can deteriorate over relatively short periods of time and should be replaced regularly.
Test methods must be followed carefully as per instructions.
Reagent tablets must be fully dissolved before you try to read the result.
Ensure that test reagents are within the best before date.
Do not mix and match reagents and test kits from different manufacturers.
If deposits or bubbles form, leave for a few minutes to clear unless the test is time specific. Bubbles can usually be cleared using a crushing rod or by tapping the side of the test tube gently.
For results that are above the range of the test, use the dilution method and test again.
Analytical instruments should be serviced.
Find out why it is important to regularly test your water here.
