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RE: mg/L or Ppm
The Amazing Metric System
<http://ts.nist.gov/ts/htdocs/200/202/mpo_home.htm>
CGS = centimeter-gram-second system
Volume
“L” is the abbreviation for “Liter” which is also 1000 cubic centimeters
which is written as cm^3 (never use cc!)
“mL” = milli-Liter = 1/1000 of a liter = 1 cm^3
Length
“m” = meter
“cm” = centi-meter = 1/100 m
Mass
“g” = gram
“mg” = milli-gram = 1/1000 of a gram
1000 g = 1 kg = 1 kilo-gram
Time
”s” = second
Density of water is 1 g/cm^3
1 Liter of water = 1,000 cm^3 of water = 1,000 g of water = 1 kg of water
1 m^3 of water = 100 x 100 x 100 cm^3 = 1,000,000 cm^3
= 1,000 kg = 1 tonne (metric ton)
1 mg of substance dissolved in 1 Liter of water =
= 1 mg/L =
= 1 mg substance in 1,000 g water =
= 1/1,000 g substance in 1,000 g water =
= 1 part substance in 1,000 x 1,000 parts water
= 1 part per million (ppm)
Quiz:
1) 1 g of Potassium in 200 L of water gives you how many mg/L of Potassium?
A: 1000 mg/200 L = 5 mg/L = 5 ppm
2) 1/4 tsp. of Potassium in 55 gallons of water gives you how many ppm of
Potassium?
A: I have no idea.
3) How much Potassium Sulfate does your 55 Gallon plant tank need?
A: A big pinch every couple of days. Try more or less and see what
happens.
(and let’s not get into how much K is in 1 g of K2SO4!)