Re: Converting mg/L to ppm?

> Also, remember that pure water at standard temperature and pressure weighs 
> one gram per cubic centimeter. 
Close, but not quite.  Did you really mean to say "standard temperature and
pressure"?  Standard temperature and pressure (STP) is 0 C and 1 atm.  At 0 C
the density of water depends on whether it is liquid or frozen.  There is a

Actually, the density of water comes closest to 1 g/cc at 3.98 C.  This is
waters point of maximum density.  The density of pure, air free water at
3.98 C is 0.999972 g/cc.

However, I doubt anyone on the list really cares about such trivia.  So, for
practical aquarium purposes, we can consider the the density of water to be
1.0 g/mL, and mg/L equivalent to ppm.