Total Dissolved Solids (TDS) test
TDS is a test which is often overlooked but is key for the overall quality of pool water. The test is a measurement of all byproducts which have accumulated during the life of the water. Water is a great absorber and holder of micron-sized particulates, such as calcium, salts, phosphates, metals, and various other tiny solids. However, water becomes oversaturated from high TDS. When the level of solids reaches the point where water can no longer absorb, it starts doing the opposite. This will occur by persistently cloudy water, scale formation, and decreased sanitizer efficiency. Testing for TDS routinely, or at least seasonally, is one of the most vital tests to perform.
While most standards do not give the maximum amount of TDS, it is recommended it should not exceed 1500 ppm over the start-up water. Should this occur, the efficiency of chlorine is reduced by 50 per cent. This means it will take 50 per cent more chlorine to properly sanitize the pool water. TDS tests are usually performed with electronic or digital meters, which are a worthwhile investment for any pool service provider.
Some other tests that may prove beneficial in the management of pool water are nitrates, phosphates, and metal tests for copper or iron. Both nitrates and phosphates are two key nutrients for algae. Testing and managing of these key nutrients in pool water is vital to keep algae blooms from appearing at times when sanitizer levels may drift low. Tests which reveal the presence of metal are paramount, especially at start-up time, and the presence of any metal such as copper or iron should ideally be addressed with the use of a metal chelator or sequestering agent before sanitizers are introduced into the pool water. If metals are not removed or sequestered, staining can occur when sanitizers are added to the water or as a result of the pH drifting up or down.
All in all, it is crucial to be proactive in managing pools, and proper testing of both the pool and source water cannot be overstated.
Author
Terry Arko is a product training and content manager for HASA Pool Inc., a manufacturer and distributor of pool and spa water treatment products in Saugus, Calif. He has more than 40 years’ experience in the pool and spa/hot tub industry, working in service, repair, retail sales, chemical manufacturing, technical service, commercial sales, and product development. He has written more than 100 published articles on water chemistry and has been an instructor of water chemistry courses for more than 25 years. Arko serves as a voting member on the board of the Recreational Water Quality Committee (RWQC). He is a commercial pool operator (CPO) course instructor, a teacher of the pool chemistry certified residential course for the Pool Chemistry Training Institute (PCTI), a California Pool and Spa Association (CPSA) board member, and a member of Pool & Spa Marketing’s editorial advisory committee. He can be reached via email at terryarko@hasapool.com.
