| Test Parameter |
|
Description |
| Calcium, Magnesium, Total Hardness |
|
Metal ions may cause interference; to prevent, add titrant containing EDTA to sample before buffer and indicator, then test as normal making sure to count drops of titrant added initially in total required to reach endpoint. If interference still occurs, dilute sample with DI water as necessary and retest. |
| Chlorine |
|
Chlorine levels > approx.?25 ppm may?bleach out indicator or cause sample to?develop?a brown color; to prevent,?add more DPD powder or dilute sample with DI water as necessary and retest. Other halogens and oxidized manganese may cause positive interference. |
| pH |
|
Iron > 10 ppm may cause negative interference., |
| pH |
|
Sanitizer levels > approx. 10 ppm may cause a blue-purple color resulting in false high readings. Wait for sanitizer level to decrease to normal levels and retest to assure an accurate reading., |
| Total Alkalinity |
|
High halogen level may change indicator reaction from green/red to blue/yellow; to prevent, add thiosulfate prior to testing. |
| Total Alkalinity |
|
Some pH modification treatments (e.g., addition of sulphuric acid) may cause interference. |