Subject: What is the actual freezing point of water (temp)

I have a question about the freezing point of PURE water.  It seems the more 
sources I check, the more different answers I find.  I have always thought 
that PURE water freezes at 0ºC or 32º F.  Your site seems to support this.  
Your site also says that water with impurities freezes at a lower point.  Here 
is why I ask for clarification.  I have found other information saying the 
exact opposite.  Some sites have suggested that it is in fact impure 
or "natural" water such as lake or pond water that freezes at the above temps. 
They suggest that the impurities in the water provide a "seed" around which 
ice crystals may form thus encouraging faster freezing.  The seeds are not in 
solution but rather suspension so that may be the difference between say salt 
and simple particles in the water.  But here is the kicker, these sites go on 
to claim that pure water actually freezes well below these conventionaly 
thought of temperatures since the "seeds" that encourage freezing are absent.  
My guess would be that PURE water still freezes at OºC or 32ºF, but maybe not 
as quickly as water with paricles in suspension.  So maybe what these sites 
are telling us (though poorly if true) that in order to get pure water to 
freeze at the same RATE as "natual" water with paricles in suspension, the 
temp needs to be lower.  Can you clear this up?

Re: What is the actual freezing point of water (temp)