TDS vs TOC?

[kaihonu82]

can someone explain the different between total dissolved solids and total organic carbons? is a low reading in one indicative of a low reading in the other? can the two readings even be relative?

thanks!

[bertoni]

TDS, as used by hobbyists, is a measure of the conductivity of the solution. TOC isn't a term I've used before, but it'd be related to TDS only to the extent that the organic carbon was influencing conductivity, which is likely not a useful measurement. I wouldn't compare the two readings, personally.

[Boomer]

TDS

If you took some salt water and removed all the water, which woud leave behind the salt, that salt is the TDS. Seawater has 35,000 ppm TDS. If we removed all the salt from 1 kg of seawater, the salt left behind will weigh 35 grams = 35,000 mg / l

TOC

All of the carbon thas is tied up in the organic matter that is in the water column.

ppm-C is a way to measure total carbon atoms in solution. It is equal to the ppm concentration of carbon atoms, regardless of what chemical form they take. It is often used to describe the concentration of dissolved inorganic carbon (DIM), dissolved organic matter (DOM), particulate organic matter (POM), or total organic matter (TOM) in seawater. It can also be used to quantify the concentration of specific carbon-containing species, such as ethanol (CH3CH2OH), but that usage is unusual.