Tom, thanks for all the great information you share.
One thing I still don't understand (although I believe you) is why optimal conditions for plant growth keep algae away. Since you're not limiting the nutrients available to the plants, these nutrients are theoretically also available for the algae. Why can't the algae use the same nutrients to thrive? Is it different micro nutrients that the algae need compared with plants? Do the plants release some sort of algaecidal chemical under optimal conditions? Why does the algae care what the CO2 level is? Regardless of the CO2 level, there is still light and nutrients available.
Jim
Because the plants define the system, not the nutrients.
That's the simplest explanation.
when you have 30-50% plant coverage, good growth etc, they will modify and control the system. Algae will wait till the seasons change to make their life cycle, much like a annuals and perennials. Algae can still do their entire life cycle, but only when it's optimal for them, the rest of the time, plants are there and grow.
Algae have a much lower level of ppm than plants do, much like you are starving the elephants to starve the mice basically. Will not work well, algae can handle much harsher conditions and leaner ppm's than any plant.
They are not really competing either, I think many are stuck on resource competition only.
One is a single cell, maybe a few cells etc, the other is Billion times larger, complex organ and tissue systems, much lower surface to volume ratio, like mice vs elephants. Fat people vs skinny people. etc.........the amount of CO2 or nutrients required to actually limit algae is many times less than it is for plants.
So the resource model goes to the algae, if you accept it as the model.
Many aquarist do/have in the past.
I think it consider Liebig's law of the minimum(google it) with respect to plants and with respect to algae, treat this like an agriculture system, or a farm or a green house, then you see you cannot limit the plants, otherwise they will not grow, but the algae will.
Something will grow, you have a choice of what that is.
So why does algae grow?
Inducement, much like warm weather and rain causes annual plants to grow and germinate. Why would they need to go to seed and die off if the weather was always nice and wet? Cold weather does not kill off all plants, nor dry weather etc.........
Perennials are fine.........
Same thing here, algae are not induced.
We also do many things to get rid of algae, limit its light, prune/trim old leaves, add more CO2 etc for the plant growth increase, add lots of algae eaters, do water changes, control all aspects of the environment, unlike what occurs in natural systems.
Read this paper from Bachmann et al:
you can see there's no correlation between nutrients and algae
WHERE AQUATIC plants are present.
That last part is key, most studies do not include that nor can, Florida has 4800 lakes 4 hectares or larger, this study used 319 lakes, more than most researchers will study in their entire lifetimes.
Non technical version:
http://fishweb.ifas.ufl.edu/Faculty Pubs/CanfieldPubs/Aquatics2004LR.pdf
Tech version
See poor R^2 values
http://fishweb.ifas.ufl.edu/Faculty Pubs/CanfieldPubs/macrophyte.pdf
General page for Roger:
http://fishweb.ifas.ufl.edu/Bachmann/Bachmann.htm
On CO2:
http://fishweb.ifas.ufl.edu/Bachmann/CO2_FL_lakes.pdf
Keep you out of trouble for awhile:duh:
Regards,
Tom Barr
