The Salt Test is used to determine the concentration of sodium chloride (salt) in pool water. This test is most important for pools using salt water chlorine generators (SWGs). Because other forms of chlorine and pool chemicals leave salt in the pool water as a byproduct, the salt test should be completed before adding salt to SWG recommended levels.
- Rinse and fill the sample tube to 10 mL mark with water to be tested.
- Add 1 drop R-0630 Chromate Indicator. Swirl to mix. Sample will turn yellow.
- Add R-0718 Silver Nitrate Reagent dropwise, swirling and counting after each drop, until color changes from yellow to a milky salmon (brick red).
- Multiply drops of R-0718 Silver Nitrate Reagent by 200. Record as parts per million (ppm) salt as sodium chloride (NaCl).
Note
- A white precipitate will form as R-0718 Silver Nitrate Reagent is added to the sample. Do not add enough R-0718 Silver Nitrate Reagent to give a brown color. First change (that holds) from yellow to a milky salmon (brick red) is the endpoint.
- Precipitate may build up in the sample tube. The sample tube can be rinsed out with water, then standard cleaning ammonia can be added to the tube and allowed to sit for a few minutes to dissolve any precipitate. Rinse the tube with water, then dry well.
- An erroneous salt reading is often the first indication of a failing cell. Salt is measured by different methods in various SWGs (see How Salt Systems Determine Salinity). It’s normal for salt readings to vary by +/-500ppm between a cell reading and the salt test kits. When test results vary between the salt test kit and the SWG, trust your test kit.
- The precision of the measurement using the 10 mL sample size is plus or minus one drop (+/- 200 ppm). With testing variances and when testing higher salt levels, the margin or error may be greater.
- Caution, if leaks or spills occur the silver nitrate reagent R-0718 will cause staining to anything it comes in contact with, gloves and old clothing are advised.
- When adding large quantities of salt, test the existing salt level and add salt in stages, retesting at each stage. Salt may take 24 – 48 hours to dissolve in summer, and longer in winter.
- To prevent potential damage to the SWG caused by high concentrations of salt passing through the cell, TFP recommends turning off the SWG for 24 hours before testing and restarting the SWG.
