is ppm the same as mg/l

wonderphil-reef

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Hi guys,

I have some Colombo Test kits and they all show results in 0,0mg/l etc
I also then have some chats that tell me what my levels should be on my water params and they all seem to be in ppm values.

Is mg/l the same as ppm or do I need to convert somehow and if so, how for Iodine, Magnesium and Phosphate?

Thanks

Phil
 

lelandmarine

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One thousanth of a gram is one milligram and 1000 ml is one liter, so that 1 ppm = 1 mg per liter = mg/Liter. PPM is derived from the fact that the density of water is taken as 1kg/L = 1,000,000 mg/L, and 1mg/L is 1mg/1,000,000mg or one part in one million
 

Randy Holmes-Farley

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While 1:1 is close enough for test kit conversions, folks should know that the true conversion is not exactly 1:1.

In seawater, 1 ppm (= exactly 1 mg/kg) is not exactly the same as 1 mg/L because 1 L does not weigh 1 kg.

1 L of 35 ppt seawater weighs about 1023 kg, so 1 mg/L = 1 mg/1.023 kg = 0.978 mg/kg = 0.978 ppm
 

taricha

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While 1:1 is close enough for test kit conversions, folks should know that the true conversion is not exactly 1:1.

In seawater, 1 ppm (= exactly 1 mg/kg) is not exactly the same as 1 mg/L because 1 L does not weigh 1 kg.

1 L of 35 ppt seawater weighs about 1023 kg, so 1 mg/L = 1 mg/1.023 kg = 0.978 mg/kg = 0.978 ppm
It's slightly annoying that "ppm" as in "500 ppm CO2" isn't even a mass ratio at all, but is a molecule counting ratio or volume ratio.
 

Randy Holmes-Farley

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It's slightly annoying that "ppm" as in "500 ppm CO2" isn't even a mass ratio at all, but is a molecule counting ratio or volume ratio.

True, a "part" can be anything, as long as it is the same thing for both for the numerator and denominator. :)
 
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