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Re: NFC: Cloudy Water

"D. Martin Moore" wrote:
> No, here's the deal.  Most often the bloom is associated with
> setting up a tank with tap water which is chlorinated.  The chlorine
> levels keep the bacteria in check.  When the water is dechlorinated
> (either through natural diffusion or sodium thiosulfate), the bacteria
> have a brief opportunity to grow.  Since the tap water is relatively
> nutrient poor (please no dissertations about phosphorus, etc.!) the
> bloom runs its course in just a few days.

The problem that I have with this explanation is that bacteria require
both an energy source and a nutrient source to survive and multiply.  In
an uninhabited, unlighted tank there is very little (if any) of either. 
Heterotrophic bacteria can certainly survive without light, but they
need an organic carbon source.  I hope that nobody has tap water that is
a significant source of organic (non-carbonate) carbon.  It's possible
that organic carbon is getting into the tank through some unknown
mechanism, but it seems unlikely.  Remember that the bacteria would need
enough nutrients to multiply extensively and cloud the water, so the
quantity of organic nutrients would have to be more than trivial.

There are certain types of bacteria, called chemoautotrophs, which can
fix their own organic carbon from CO2 or carbonate.  As far as I know,
the nitrifying bacteria are the only bacteria of this kind that inhabit
aquariums.  Since we already know that the tank is uninhabited, there is
no source of ammonia to provide these bacteria with energy.  Also,
chemoautotrophs are very slow-growing and could not account for a sudden
bacterial bloom.

> The bloom has really nothing to do with the temperature.  Nor are
> the levels of dissolved salts in tap water approaching saturation.
> Nothing would be able to live in such a strong chemical solution.

Many dissolved salts have very low solubility product constants, and
their actual concentration in water is very low even at saturation.  

Andrew Dalton


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