TDS as a measure of water quality has limited value. It can be somewhat useful in certain cases, but you have to know how to understand the tests.
For one thing, many contaminants will become a problem well before they would cause a significant increase in the TDS.
Metals will cause noticeable issues at very low levels. Copper, iron, manganese, silver etc all are problems at low ppm.
Phosphate or sulfate would begin to create strange scale well before they would create enough of a TDS increase to raise concern.
Bromide would register as salt on a drop test or a conductivity test. In conjunction with dimethylhydantoin, bromide would convert chlorine to bromine and the dmh would lock up the bromine making the pool unmanageable.
Lithium or magnesium might not be a problem and could spike the TDS, but they usually would come in with chloride, so they would coincide with a chloride drop test or conductivity test.
Anything that would spike the TDS reading without being accounted for in the regular tests would probably be noticeable as problems of some sort.
Most regular components of the TDS can be measured. Total alkalinity, calcium, cyanuric acid and salt are all measurable and we know the correct ranges.
The TDS readings as done by the pool stores are, in my opinion, completely worthless and incorrect.
If you did get a salinity test from a salinity meter that was more than 1,000 ppm higher than all of the TDS components measured separately, that could indicate a problem.
In most such cases, the water will already be unmanageable and there will be obvious problems.
In such a case, you would probably need to drain and refill. Trying to find the cause would probably take a scientific chemistry lab that could do complete testing. Even then, draining and refilling or reverse osmosis would probably be the only viable solution.
Bottom line:
All chemistry that matters can be measured by the regular test kits that we recommend.
A TDS reading from a TDS meter is not accurate for salt pools. A salt meter is the correct meter.
Compare the SWG reading to a K-1766 drop test periodically and compare both to a salinity meter reading periodically if available. Investigate if the numbers are more than 800 ppm different.
Anything in the water that's going to cause a significant TDS spike will be obvious in most cases.
For one thing, many contaminants will become a problem well before they would cause a significant increase in the TDS.
Metals will cause noticeable issues at very low levels. Copper, iron, manganese, silver etc all are problems at low ppm.
Phosphate or sulfate would begin to create strange scale well before they would create enough of a TDS increase to raise concern.
Bromide would register as salt on a drop test or a conductivity test. In conjunction with dimethylhydantoin, bromide would convert chlorine to bromine and the dmh would lock up the bromine making the pool unmanageable.
Lithium or magnesium might not be a problem and could spike the TDS, but they usually would come in with chloride, so they would coincide with a chloride drop test or conductivity test.
Anything that would spike the TDS reading without being accounted for in the regular tests would probably be noticeable as problems of some sort.
Most regular components of the TDS can be measured. Total alkalinity, calcium, cyanuric acid and salt are all measurable and we know the correct ranges.
The TDS readings as done by the pool stores are, in my opinion, completely worthless and incorrect.
If you did get a salinity test from a salinity meter that was more than 1,000 ppm higher than all of the TDS components measured separately, that could indicate a problem.
In most such cases, the water will already be unmanageable and there will be obvious problems.
In such a case, you would probably need to drain and refill. Trying to find the cause would probably take a scientific chemistry lab that could do complete testing. Even then, draining and refilling or reverse osmosis would probably be the only viable solution.
Bottom line:
All chemistry that matters can be measured by the regular test kits that we recommend.
A TDS reading from a TDS meter is not accurate for salt pools. A salt meter is the correct meter.
Compare the SWG reading to a K-1766 drop test periodically and compare both to a salinity meter reading periodically if available. Investigate if the numbers are more than 800 ppm different.
Anything in the water that's going to cause a significant TDS spike will be obvious in most cases.
