So is there any data on the sediments in these same locations and does this include typical values all year, or just at the time the folks decided to take the measurements?
You leave out the sediments and other critical aspects, then it really no longer supports such contentions
Kasslemann made a big deal with water column, but then did not bother to test the sediments(I asked her directly in person). The plants are obviously growing and the ferts need to come from somewhere. She turned and went the other way quickly. If you study aquatic weeds, you know they are growing well, they must be getting the nutrients from somewhere, the water or the sediment. Also, while the habitat for the plant sis rather small, the river is really massive and unidirectional massive flow, so the plants never run out of the very low level of nutrients really........whereas we do not have this option for aquarium management.
Rather than testing and relying on other folk's data, why not test and see for yourself?
I have Erios, wimpy Rotala's, Hydrothrix, and a dozen other stem plants that are considered tougher.........and yet I can garden and scape very easily and without much effort, but...I am consistent.
I have no issue growing any species you can name. Some plants do quite well in lean or rich sediments, or lean or rich water column also.
The polish claims on D diandra are entirely false, I have some of the densest D diandra in my 120 Gal and SAPS, SFBAAPS members have seen it in person, there's no such issue. All it takes is for a few folks to falsify such claims to invalidate them as the sole reason.
This is VERY easy weed to grow in EI or most any other routine.
Funny, I have 7ppm of PO4 in this tank.......just look at all that stunting.........
3. I agree on that, but neither does high nutrients and high light, nor does low light and low nutrients..... either.........
maybe it's less to do with nutrients as far algae?
4. I'm not sure what maxing out CO2 means really, I add just enough for a particular tank, sometimes this is 60-70ppm, sometimes 40ppm, depends on the tank. Also depends on the plant species involved.
I have little issue growing any species and gardening with it, I dose these so called issue level ppm's and find no adverse effects.
Maybe I have a magical wand that grows plants?
Regardless, the point is in the results above, it does not state why they had problems, of which there maybe be MANY, it only states, very precise, and clear.....what it cannot be due to solely independent of other factors.
EI or ADA, or most methods are not particularly precise, nor do they need to be. Aquarist mess many things up and blame nutrients for it, does not mean that nutrients are the blame.
Unless you are careful and test each one, step by step to see if it's true, you cannot know and even then.....all it takes is for one or two people to falsify what you thought was true.
You can rule out and falsify a hypothesis like thos eproposed, and I think you can see clearly the lack of support the above 120 Gallon ilustrates. Rather than squabble, let's pony up and show results that support your contention rather than starting off with a "pre drawn" conclusion.
You add things, test and see if you can disprove your hypothesis. If you cannot, then you tentatively accept that hypothesis as true.........but, that does not imply you did not have an issue in your test methods......nor that it is true. All it takes is for someone who does add high PO4 to D. diandra to blow that claim out of the water.
We have plenty of local members who can attest to the results also.
BTW, what are your CO2 and light levels since you state that they are very high?
Mine sit at 50-60umol in the above tank. Same as ADA's tanks.
Amano seems to manage and eek by with his scapes at these same light intensity curiously. The top ranking ADA contest tank has 40-50umol of light.
Rich sediment is also dosing high levels of nutrients, just a different location.
Just because low ppm's of nutrients exists at that point in time of the grab sample/season, does not imply that habitat is always like that , nor does this imply that it is best for horticulture either.
ADA tends to use the sediments more than the water column.
I use both, but ADA and myself do seem to use the same light, the same water changes and the same care routines and focus on gardening. I arrived at this stuff independently.
Seems like good advice to me.