While unbalanced water, algae, heavy rains, heavy bather use and other problems can cause sudden changes to test results, the problem might also be the kit or strips, water sampling technique, or testing methods.
- Check to see that the kit or strips are not out of date.
- Be sure to follow label directions on how to do the test. Failure to use the correct procedure may cause errors in results.
- Always let the water circulate at least 30 minutes to one hour prior to testing.
- Take the water sample away from the skimmer or a return. Use the "elbow-deep" guide for taking the sample.
- Do not use old or expired test kits or strips.
- Keep test kits or strips out of the heat and direct sunlight.
- Establish a routine for testing; day of the week, time of day, etc.
- Be aware that heavy rains, heavy bather loads and other conditions can cause significant changes to water balance, sanitizer readings, etc.