Re: nutirent uptake graph

[Thomas Barr <tcbiii at earthlink_net>]

> I have questions on the nutrient uptake rates graph.  Is the graph plotted
> for general nutrient uptake or specifically for PO4 uptake?

Nutrients.

> Will the
> uptake rates be similar for nutrients like K, NH3, NO4 & etc.?

*Generally*, yes. There's always exception and special cases.

> BC (Singapore)

It's a simple graph but taking a good look at it will explain quite a bit.
Uptake rates and affinity for P, Fe or N species(the most common limiting
nutrients for various algae and plants in aquatic systems) are higher as the
size of the plants/algae decreases. As the nutrients increase, the rate of
the oligotrophic algae level off, but the Eutrophic plants, continue to
increase the uptake rates.
This is mainly the competition component. The disturbance
component(Herbivores, us scrubbing the algae off and manually removing it,
water changes etc) is another.

I believe that the photorespiration, and high ambient levels of O2 cause the
most damage to algae though.

Plants can get by with less PO4 and survive better on low limited PO4 than
many of the other nutrients. Fe also at lower lighting levels. NO3 to some
degree also. But this in not "optimum plant growth" even at these lower
lighting ranges. I've tried it. So have others. Algae was still there and
did not disappear. 

It works and you can get acceptable result doing that method. But you can
have better results by removing the plant limitation and have less
algae/better plant growth. The substrate can be a very reductive environment
and when folks uproot plants for pruning, up comes the iron, the PO4 and the
NH4. The iron and PO4 are not the problem as many like to point to
accusatory finger. It's the NH4.

NO3/NH4 is the biggest source of issues for folks after CO2. Limiting
approaches work, but the also limit the plants. That, IMO is not an "Optimum
Aquarium". It also does not fully explain what happens with plant algae
interactions in our tanks. It only explains slowing the system down. You can
do this better IMO using lower light and scrub the algae/add herbivores to
the needed work to remove the algae down to acceptable levels. Plants will
look better. 

Regards, 
Tom Barr 


 

 


Regards, 
Tom Barr