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Green Water



Steve Dixon wrote:

> > Since I'm on a roll, how about a 3rd question?  I've been practicing
> > "patience" with a green water problem in my 3 mo. old rainbow tank.
> > I've been testing to see if anything unusual is going on.  The biggest
> > surprise is nitrates.  Despite the fish load and the addition of 4-8
> > mg./l nitrate (from KNO3) at water changes, the nitrates drop to 0.0
> > (LaMotte) within a few days.   Other tank parameters:
> >
> > 40 gal. reg; pH 7.2 (mornings) ~7.4 (afternoons); GH 5; dKH 10
> > CO2 12-20 mg./l; phosphates - always 0.0 (Hach)
> [BIG SNIP]
 
Mark Pearlscott wrote:
 
> This is very interesting.  Both your nitrates and phosphates read zero?
> What is your turbidity like?  How often do you test the tank water?  How
> often do you do the water changes?
> 
> It's true that most micron cartriges have a hard time filtering out
> green water.  You might try one of those particulate binding
> (coagulating) products to see if that does the job.

I had a similar situation. NO3 and PO4 measured 0 despite daily
additions of PMDD. Iron also measured near 0. Still the green water
flourished. This would seem to indicate that the green water is very
efficient at removing nutrients from the water. During this time, I had
no other green algaes present in the aquarium. The only other algae
present was some dark brown to black filmy stuff that was hard to
remove. An H.O.T. Magnum with the micron cartridge in had no effect on
the algae.  

Roger Miller wrote:

<Snip>

>    Green water blooms were related to iron fertilization.  I stopped using
> it and the green water disappeared quickly.  I let the tank stabilize and
> afterwords I was able to gradually worked the fertilizer back up to a
> useful level.

This makes sense. Roger, how did you "let the tank stabilize" ?

Pat Bowerman