Make sure you splash and rinse out the tester prior to collecting your sample to eliminate possible contamination. Repeat this process between pH, alkalinity, and chlorine tests. Most pool companies require at least 8oz. of water for pool water testing. If you're looking for the best way to test pool water, using a liquid test kit is advised. These testing kits offer the most accurate readings. And, while using them may be a bit more involved than using test strips, they are still relatively user-friendly.