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Re: GH and green water

Roger S. Miller said...

>On Wed, 25 Aug 1999, Dave Whittaker wrote:
>> I was surprised that no one commented on my previous post concerning
>> the disappearance of green water subsequent to the addition of dolomite
>> to three tanks.
>Well, I meant to but I got distracted.
>Phosphate combines with calcium to produce some pretty insoluble
>compounds.  I thought that maybe by increasing the hardness you
>precipitated or sequestered the phosphate so the algae could no longer
>grow.  What I don't really understand is why that mechanism or any similar
>nutrient-related mechanism would cause such a drastic disappearance of the
>algae.  It seems to me like disappearance due to starvation should be
>fairly slow - especially since the nutrients contained in the first
>cells that die would be at least partly recycled and be available to
>surviving cells.

This was fairly quick -maybe three days.

>Perhaps there are two or more mechanisms at work.  For instance, some
>single-cell animals like paramecia are important algae grazers and act as
>natural control on algae blooms.  Perhaps your green water tanks contained
>a fairly delicate balance between the green water and the grazers.  If
>something (like calcium making phosphate unavailable) slowed the algae
>growth then the grazers could quickly wipe out the standing crop of algae
>fairly quickly.  The grazing population would have died afterwords, as

One would expect an algae rebound at this point, but the water in the
15 gallon remains clear so far. I probably should remove the plantlife
and observe the effect if any.

Dave Whittaker
Gloucester, Ontario
ac554 at FreeNet_Carleton.ca