Total Disolved Solids (TDS)

[bmgo]

Just got my water checked.
Total Disolved Solids (TDS) was mentioned my is 400 and I was told that that was great. I feel god but what the #$@^ is TDS and how can I control it or is it POLL GUY selling?

[Watermom]

Forget about the TDS. Nothing you need to worry about. Just maintain proper chemistry and you are good to go.

Watermom

[mas985]

TDS stands for total disolved solids and is basically all of the minerals in the water. This material can include carbonate, bicarbonate, chloride, sulfate, phosphate, nitrate, calcium, magnesium, sodium, organic ions, and other ions. TDS has a very minor impact on saturation index. In fact, most calculators leave it out. It usually does not cause a problem unless it gets too high.

[CarlD]

It's a fancy test that pool stores use to impress you. Like acid demand and base demand it is virtually useless.

Ignore it.

[mas985]

Carl, I know that many people have not bought into the Langelier Saturation Index, but there is a bit of science behind it and it is not just used by the pool industry. Water treatment pants have been using it for years to prevent scaling in the water system. Yes, if you keep your numbers in recommend range, the LSI is fairly close to zero so you do not have to worry about it. However, sometimes pool owners have to work with high calcium hardness levels which LSI can help target proper alk and PH so that scaling will not occur. LSI gives me piece of mind knowing I went the extra mile to make sure my numbers are right.

Here are a few links if you are interested:

http://www.lenntech.com/langelier-index-eng.htm
http://www.awt.org/members/publicati...l/Fall1991.htm
There are many more you can get with google.

[CarlD]

As you say--in very peculiar fill water conditions the TDS and SI tests may be useful. (the question was about TDS, not the SI)

But for 99.9% of us, our problems are due to NOT following the procedures Ben recommends. And they go away when we follow them.

[waterbear]

Carl, I know that many people have not bought into the Langelier Saturation Index, but there is a bit of science behind it and it is not just used by the pool industry. Water treatment pants have been using it for years to prevent scaling in the water system. Yes, if you keep your numbers in recommend range, the LSI is fairly close to zero so you do not have to worry about it. However, sometimes pool owners have to work with high calcium hardness levels which LSI can help target proper alk and PH so that scaling will not occur. LSI gives me piece of mind knowing I went the extra mile to make sure my numbers are right.

Here are a few links if you are interested:

http://www.lenntech.com/langelier-index-eng.htm
http://www.awt.org/members/publicati...l/Fall1991.htm
There are many more you can get with google.

The LSI was designed for closed systems and not for open systems such as pools. Ryzner and Hamilton indecies are also sometimes applied to pools and what is 'balanced' under one is not necessisarily 'balanced' under another with the same readings.

pH is the only factor in the LSI equation that is used as a direct reading and therefore has the greatest impact on whether the water is corrosive or scaling. The alkalinity and hardness readings can change a lot and only have minimal impact since it is the log of these readings that is used in the equation.
As far as TDS is concerned, if it is a problem as some would make claim to then every pool with a SWG should be in big trouble since the TDS will be AT LEAST as high as the salt level in the pool (usually about 3200 ppm!) and, in reality, will be higher because of the hardness, alkalinity, sulfates (if dry acid is used) , etc.

IMHO, neither one is anything to loose sleep over.