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RE: Nutritional Problem

> From: Henry Hatch <hhatch at sprynet_com>
>
> After attempting to identify a nutritional problem in my tank for the
> last month I finally have determined that my tank appears to be nitrogen
> limited. I added KNO3 to the water column which brought nitrate levels
> to about 13 ppm, a rather high level. My plants which had been growing
> poorly or not at all, suddenly responded and new growth appeared.
> However, the algae also started to grow very rapidly. In less than 48
> hours my nitrate level was 0 according to my Lamotte test. The plants
> stopped growing and I'm back to square one.

Not everybody here will agree with what I am about to say.  This is what *I*
would do based on my own experiences.

It seems obvious from what you have written that your tank is nitrate
limited.  This probably means that uptake of other nutrients is restricted,
causing there to be plenty of them available, including the dreaded P.

When you add N to this mix you perhaps have plenty of everything available,
causing everything to grow well, including algae.

I would continue to add KNO3, maintaining 5 to 10 ppm (as is SOP here).  13
is not a level to cause concern.

I would expect some algae problems when you do this until the other
nutrients present in your water column are consumed by the plants, as they
will be once the N shortage is corrected.

A substantial water change before you add the KNO3 would attenuate this
potential problem.

I have never used any phosphate filtering material, but I would consider
doing so in your situation.

Good luck!

Frank.
-----
The very act of seeking sets something in motion to meet us;
something in the universe, or in the unconscious responds as if
to an invitation.  - Jean Shinoda Bolen

http://home.istar.ca/~fir