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	Hi Susan etal.  I just wanted to mention that cycling a tank at a
pH below 7 is not necessarily safer:  while it's true that relatively
non-toxic ammonium predominates such pHs, nitrite toxicity _increases_ at
lower pHs.  Why? Because nitrite and nitrous acid exist in an equilibrum
similar to ammonia/ammonium.  Nitrous acid predominates at pH below 7 and
is much more toxic than nitrite, because it is non-charged and therefore
does not require ion-transport channels, its passage through the gill
epithelium is not inhibited by competing ions (such as Cl-) etc.