Re: Electro-Right, RO-Right, etc.

> The bottle of Electro-Right states "Deionized water is too pure for
> freshwater tropical fish" and "these "hydrominerals" are necessary for
> proper gill function, regulation of blood pH, oxygen uptake, and other
> metabolic processes".

   Frankly, this stinks of fraud.  Deionized water is NOT too pure for
fish to live in in any way.  There is no essential mineral fish need
that is not more easily obtained from their FOOD--their ability to get
some minerals out of their water is at best a sort of back-up in the
event their diet becomes partially deficient in an essential mineral.
(And even then it's not always enough to save the fish from developing
symptoms of the deficiency.)  As far as your fish NEEDING the minerals,
that's certainly true, but any statement to the affect that fish need
trace minerals in their water is, to put it politely, suspect.
   (I'm reminded of a marketing maxin that goes to the effect of
'either find a need and create a product to fill it, or find a
product and convince people they need it,' the point being that all
too often companies trying to sell you something will just as happily
sell you something you don't need as they would sell you something
with practical value.

> We are totally in the dark about what is "necessary" for fish health as
> far as "hydrominerals" are concerned.

   We do have some fairly good numbers for commercial food fish like
trout, catfish, eels, etc.--there's enough similarity between them that
we can take some guess at what our tropical pets need.  (And wouldn't
you know it, there's a good supply of all the essential minerals in
meat and fish meal, the basic ingrediants of almost all fish foods. :-)
(And what's a "hydromineral" anyway?  It's not a term I've heard used in
any scientific field--I wonder if it was coined by the marketting folks
as a 'trendy' way of saying water soluable... :-)

> Would the CaCO3 be all that we would need
> to add back into the DI water?

   That would be my opinion.  A little calcium carbonate to provide
some pH stability and a little carbonate hardness for plants is the
only thing I can think of that really makes sense to add back to
RO/DI water.

Nathan H.
In surprisingly warm (15 degrees) Fargo ND. :-)