pH = -log[H+] ..... [H+] is the concentration of hydrogen ions (= protons) measured in Eq/l (that's equivalents <number of charge, or in H+ = number of molecules> per liter) .... pH itself has no units.
KH is a measurment of the
HCO3 &
CO3 concentration ... this is measured in
mg/l <milligrams per liters> which is the same as
ppm.
KH is also measured in degrees hardness (dH) -- 1mg/l = 0.056 dH. Note that the dH is US measure, there is also German degrees & grains (British?) hardness. You can also convert
ppm to mEq/l. For
CaCO3, 1mg/l = 0.02 mEq/l.
Picky technical note - typical
KH kits do not measure
KH! The kits actually measures total alkalinity, although the unit is expressed as the equivalent
KH. (ie dKH)
NH3,
NO2,
NO3,
PO4,
Ca,
Fe are all measured in
mg/l (=
ppm). You can covert to mEq/l by dividing
ppm by the respective molecular weight then multiply by the number of charge of the molecule.
Specific gravity has no unit. This is a measure of density as a ratio to pure water.
Water's density = 1g/ml or 1Kg/l
if you add (say) 10 g of salt to 1l of water, the density of that salt water is (1000g + 10 g)/l or 1.010 Kg/l.
specific gravity = density of salt water /density of water ....
in this example
sg = 1.010 Kg/l / 1.000 Kg/l = 1.010 .....
ie. to get specific gravity, you just calculate the density in Kg/l & drop the units!
