Okay. This interests me. Everyone is correct and nothing said to date has been correct.
TDS does matter. However more importantly TDS make up matters.
Old thinking was the TDS is left over chemical ash that can interfere with chemical reactions making them slower and the affected water body can go off colour.
Observationally in one country where it is sub tropical rain forest if TDS in a chlorinated pool exceeded 1500 mg/l (100 out of the tap) water body would go green and no amount of chemical would fix it. Consequently drain and refill. Therefore TDS is obviously the culprit.
In a second country in a semi arid climate the tap water TDS levels in excess of 600, water bodies often having levels of 4000 or more with no apparent effect.
TDS does matter. However more importantly TDS make up matters.
Old thinking was the TDS is left over chemical ash that can interfere with chemical reactions making them slower and the affected water body can go off colour.
Observationally in one country where it is sub tropical rain forest if TDS in a chlorinated pool exceeded 1500 mg/l (100 out of the tap) water body would go green and no amount of chemical would fix it. Consequently drain and refill. Therefore TDS is obviously the culprit.
In a second country in a semi arid climate the tap water TDS levels in excess of 600, water bodies often having levels of 4000 or more with no apparent effect.
Therefore TDS is obviously not the culprit.
How can both observations be true?
TDS or Total dissolved solids is a conductivity measurement of the water. The actual measurement is the measurement of the amounts of anions present. Anions being chloride, phosphate, nitrate and so on.
Some anions have a greater impact on TDS than others. As a rule of thumb chlorides generally makes up 67% of the TDS we measure.
Going back to our two different countries, and unless you have had this exposure you wouldn't have realised this, the two mains waters are very different. Consequently one has 600 plus the other 100 maximum out of the tap. The water with 600 mg/l is from ground sources, the 100 from dams. This means the make up of the water is different. Ground water contains more chlorides (in this instance anyway, could be carbonates, sulphates etc). Consequently the TDS is reading higher.
Look at the two climates. One is sub tropical rainforest - this means lots of organics in the atmosphere and also a lot (comparatively) of rain. The other semi arid with not much organics load and little rain.
The indications from the observation and the chemical is, and it is only an opinion not based on anything but observations and thinking, that it is likely the water body going green over 1500 mg/l is containing higher levels of phosphates, nitrates and other organics anions than the water body in the semi arid climate. Therefore the make up of the TDS is different. Consequently the outcome is different.
I think there is some truth to the phrase 'Good and bad dissolved solids' based on very limited observation in the field. It would be interesting to gather more data and see if the hypothesis holds true.
However, yes of course salt being sodium chloride adds significantly to the TDS level. I don't think there is any harm from TDS which is primarily chlorides.
How can both observations be true?
TDS or Total dissolved solids is a conductivity measurement of the water. The actual measurement is the measurement of the amounts of anions present. Anions being chloride, phosphate, nitrate and so on.
Some anions have a greater impact on TDS than others. As a rule of thumb chlorides generally makes up 67% of the TDS we measure.
Going back to our two different countries, and unless you have had this exposure you wouldn't have realised this, the two mains waters are very different. Consequently one has 600 plus the other 100 maximum out of the tap. The water with 600 mg/l is from ground sources, the 100 from dams. This means the make up of the water is different. Ground water contains more chlorides (in this instance anyway, could be carbonates, sulphates etc). Consequently the TDS is reading higher.
Look at the two climates. One is sub tropical rainforest - this means lots of organics in the atmosphere and also a lot (comparatively) of rain. The other semi arid with not much organics load and little rain.
The indications from the observation and the chemical is, and it is only an opinion not based on anything but observations and thinking, that it is likely the water body going green over 1500 mg/l is containing higher levels of phosphates, nitrates and other organics anions than the water body in the semi arid climate. Therefore the make up of the TDS is different. Consequently the outcome is different.
I think there is some truth to the phrase 'Good and bad dissolved solids' based on very limited observation in the field. It would be interesting to gather more data and see if the hypothesis holds true.
However, yes of course salt being sodium chloride adds significantly to the TDS level. I don't think there is any harm from TDS which is primarily chlorides.
