If you were to make a list of critical pool water chemistry to monitor, would you include total dissolved solids?
Surely you would include chlorine, pH, alkalinity, and hardness, yet you may not pay much attention to TDS . TDS can be critical - don’t ignore it!
It is always a good idea to test the TDS at least once a month in pools, even more frequently in spas, and most importantly, whenever there is a problem. For proper swimming pool and spa maintenance, NSPI suggests the following operational guideline levels for TDS: 300 ppm - minimum, 1000-2000 ppm - ideal, 3000 ppm – maximum, or 1500 ppm maximum at pool startup. Pools with salt generators can generally maintain a slightly higher level. The primary component of TDS in these pools is sodium chloride, which is very soluble.
There are two ways to measure TDS levels. A portable conductivity meter is one common method. TDS meters measure conductivity of certain species in a sample and then use factors to compute guideline TDS ppm values. These instruments require periodic calibration to maintain accuracy. As an alternative to the conductivity meter, an inexpensive, dip-and-read test strip has been recently introduced that allows you to obtain TDS readings. You simply compare the reacted color of the strip to a color chart to determine the TDS level. It is simple enough that anyone can use it, and it does not require calibration.
Armed with this information now you’re ready to keep the TDS in line. Adding total dissolved solids to your list of critical water parameters to monitor will help you maintain healthy a pool or spa. If you overlook TDS you may waste time and dollars trying to troubleshoot water balance problems.