The National Pool Industry Research Center in San Luis Obispo, Calif., studied the overall precision of selected test kits. The chart below summarizes the precision results for each test kit.
| OVERALL PRECISION SUMMARY | ||||||
| Kit | Free Chlorine | Total Chlorine | Total Alkalinity | pH | Calcium Hardness | Average |
| (Percent deviation from lab value) | ||||||
| AquaChek (strips) | 14.3 | 14.5 | 21.7 | 36.0 | 34.9 | 24.3 |
| AquaChek (DPD) | 4.6 | 9.2 | 9.2 | 16.0 | 10.9 | 10.0 |
| Guardex (DPD) | 19.1 | 23.4 | 10.0 | 12.8 | N/A | 16.3 |
| Guardex (OTO) | 19.1 | 23.5 | 14.0 | 8.8 | N/A | 16.4 |
| LaMotte (strips) | 8.7 | 9.2 | 26.1 | 29.1 | 24.2 | 19.5 |
| LaMotte (DPD) | 33.5 | 44.0 | 13.6 | 25.4 | 16.2 | 26.6 |
| Pentair (DPD) | 29.5 | 29.5 | 13.3 | 9.0 | N/A | 20.4 |
| Pentair (OTO) | N/A | 13.0 | 12.6 | 25.7 | 23.5 | 18.7 |
| Pentair (strips) | 34.7 | 39.8 | 21.4 | 23.7 | 21.5 | 28.2 |
| X-Kit 1 (DPD) | 16.1 | 16.0 | 5.7 | 16.7 | 8.9 | 12.7 |
| X-Kit 2 (strips) | 15.3 | N/A | 15.0 | 22.4 | N/A | 17.6 |
| X-Kit 3 (DPD) | 15.2 | 17.9 | 10.0 | 13.9 | 15.2 | 14.5 |
| Jack's Magic (DPD) | 29.2 | 37.6 | 19.4 | 8.3 | 20.5 | 23.0 |
| Palintest 9(photometer) | 2.6 | 0.0 | 3.4 | 4.6 | 2.6 | 2.7 |
| Average | 20.0 | 23.1 | 14.8 | 19.1 | 19.5 | 19.1 |
