Aquadream said:
You seem to have a lot of empirical experience, but I am more interested in the academic side of things.
If you have well tested Redfield Ratio you would have seen the effects of that theory. PO4 been 10 times lower than NO3 is well explained there and I have extensive tests experience with it.
Higher PO4 levels can also work, but there are more factors to be taken into account then.
Which is to say PO4 thus the ratio itself, is independent, thus does not matter in the context of aquatic plants,.
The RR is perhaps the single most abused concept in aquatic biology.
Charles on a Dutch site also abused this and made some poor assumptions and got caught.........but then did not correct the error when notified several times. He also made a mess and did not realize the difference between atomic rations and mass ratios. RR is an atomic ratio, not based on mass.
Plant ratios tend to be 7 N : 1 P or about 10 NO3 to 1 PO4.
This is what is found in nature, this does not imply what is best for horticulture and aquarium plants.
Iron does help enhancing colours when they are not at their best. And if in excess it will cause algae as will any other nutrient when added too much. Call Amano for advice on this subject.
I add nearly 2-3ppm per week of Fe, I do not have any algae management issues. This is a myth.
I have done this on many tanks over 15 years or more now.
Fe is a general co factor in enzymes, few of which help form reduced carbon chains that form the color specific pigments, but do help in general cycling and growth of many other factors. The red in the plants has no Fe in it.
Rocks do that are red generally, but not plant pigments.
As far as a research on Fe uptake Haller (1977) has the only known paper out on Fe uptake in submersed aquatic plants that relates to growth and max uptake:
8 ppm was the highest rate of growth, and 6 ppm was the highest rate of uptake for Fe.
Quite juicy.
http://www.sciencedirect.com/science/ar ... 7077900390
This is 80X what many aquarist seem to suggest, I am not one those aquarist
🙂
I suggest about 0.5-1.0 as proxy per dose and tend to dose 3-5x a week personally.
When you talk about CO2 do you know what is the concentration of it in the natural South American waters where most Alternanthera species originate. Most of those waters are acidic IMO and no one there is pumping CO2.
These plants are not underwater much, they are amphibious, thus do not require much other than the survive till the dry emergent period occurs, others, like Hydrill, Vals, Egeria , pondweeds etc, all have evolved bicarbonate methods for CO2 uptake.
It really depends on where you are talking and the density of the plant biomass etc, some places like Bonita spring, Mato Grosso are Full of plants, and the CO2 is quite high, over 20ppm all year all the time, same with many Florida springs in the USA, and in Australia and IndoChina.
This is where we find the optimal habitats we like, clear flowing waters full of fish and plants.
I've got lots of pictures of these places.
The idea of CO2 huge needs in aquarium is no more than a fast growing cabbage theory and may be good for people that are so much in a hurry to grow plants, but it is completely different from any process in nature.
Tell that to these springs:
This is Natural. I pose this question often in talks........not everywhere is rich in CO2, but plants can still manage, they grow, but grow slower. when they have less CO2, they start to strongly compete with one another, this is why we have little trouble a dozen or more species together in CO2 enriched tanks, but they do poorly except for a few species in a non CO2 tank.
Nutrients and light can easily be made independent in a non CO2 tank to test this also.
Support coems from Bowes , Haller and Van, 1976, light curves and the difference between say Hydrilla and say Cabomba are huge, Hydrilla will remove all the CO2 asap as light enters the pond/lake/stream etc. Cabomba has not even started photosynthesizing yet, Hydrilla is very aggressive, Egeria etc is as well. We have all these weeds in CA where I do management of invasive aquatic weeds.
SOB's they are too.
CA springs:
FL:
Me in one such spring:
Guess what this plant is:
It is not Ammania
Search Botina springs, Pupu spring on google for more, or San Macros River in Texas etc.........
Bowes, Haller, Van's paper, old but good and few are done like this anymore:
http://www.plantphysiol.org/content/58/6/761.full.pdf
Be nice if they did this for 200-300 species we cultivate...........
ceg4048 said:
Althernanthera does not really care about pH. What it cares about is CO2. When higher levels of CO2 gets added this causes a a greater drop in the pH, giving the illusion that a lower pH is necessary. Trying to manipulate pH in planted tanks is a mistake and should be discouraged.
It is precisely the adding of more CO2 that manipulates the PH in aquarium. Perhaps you can change or correct this statement of yours as it appears to be a huge contradiction.[/quote]
I can have a pH of 6 and 30ppm of CO2, or I have a pH of 7 and 30ppm....only the KH is changed......but the plant does not care....in both cases the plant has ample CO2.
In this case I moved the KH and pH, but left the CO2 the same in each case.
This is about 1 degree(17.86ppm) KH vs say 8-10 degrees, something close, you can look it up on the tables........if you wanna.