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Re: Nutrients vs. algae

BC and APD Gurus,

In one of my tank the levels are

P04  > 10ppm
N03 <  5ppm
Fe   < 0.1ppm
CaCO3  260ppm (tube well water)
pH   ~ 6.5 with C02
water depth 15"

My macronutrients of NPK are in the ratio of 1: 0.15: 0.8
with magnesium. I am currently experimenting with the
following mix @ 3ml per day into a 50 gal:

Water   to make 1L with
KN03       100 gms
MgNO3      150 gms (Magnesium Nitrate)
H3PO3        25 ml
(^sometimes I leave out ortho-phosphoric acid when the PO4
levels exceeds 10ppm)

I have exellent growth and very little algae.

I feel that P04 levels have been misunderstood and maligned.
Now that a lot more aquatic planters are out there and
more varied information is availabe. We must look at the
overall nutrient picture. The depth of the planted aquarium
should be factored into the equation.

I have noted that in outdoor/naturally lit aquaria (opaque sides),
when the water depth is greater than 15" the plant growth
slows down and the growth stops completely at 30" even in
full sunlight... green water sets in. Algae which can cling to
walls thrive in deep water situations in the region of surface
to 12" below.. Just reducing the water levels in these tanks
has resulted in spurt of growth in plants and dramatic drop
in hair algae.

(This is not the same with my shaded outdoor glass aquaria.
Light also enters via the sides and changes the equation.
Lighting a glass aquarium from the sides might make an
interesting study in indoor transparent aquaria.)

I presume that water depth plays a  part greater than can
be attributed to lesser light at greater water depths.

(By water depth I mean the measured distance from the
surface to the top of the substrate.)

Raj, vu2zap
Bangalore, South India

>From: "Lee Boon Chuan" <lee.bc at ellipsiz_com>
>Subject: Nutrients vs. algae
>The PO4 level in my tank has stay at 40ppm level for a least 2 weeks
>while my NO3 is at 20+ppm.
>My tank now reads:
>PO4     40ppm
>NO3     20+ppm
>Fe      0.5ppm
>GH      8
>KH      3~4
>pH      6.0
>Lights  3.4W/gal
>Many people would have expect an algae outbreak under such conditions.
>But in contrary, I have yet to see any increase in algae growth.
>I am beginning to buy into Tom Barr's idea that nutrients limitation
>is not the way to prevent algae growth.  However, up till now there
>has not been any mechanism confirmed to have prevented the algae
>If it is true that we need to maintain sufficient nutrients for the
>plants in order to stifle the algae growth.  Should we just simply add
>as much nutrients as possible in order to be sure that none of the
>nutrients is lacking.  Is there still a need to control the nutrients
>at a certain level?
>In my case, the excess PO4 has yet to cause any trouble in my tank.  I
>am curious in what you guys think.
>BC (Singapore)