The problem is that whenever NO3 is close to 5 ppm such plants as alternatera reineckii and umbrosum get stunted and stop to grow. If NO3 stays at 10 ppm the plants die. Only when i keep NO3 at about 2.5 ppm the plants grow without any leaves deformations. However Blyxa japonica and h.callitrihoides grow slower at lower NO3. CO2 is good, it's usually 20 ppm.
I know some people can grow the plants i've just mentioned about at high NO3 and soft water but i can't understand how they do it... I'm going to try another micronutrient which, as literature says, may by also an important element having affect on micro and macro uptake in plants
You spent all this effort but you did not measure light nor CO2 effectively.
CO2 changes and the rate of change is dramatic.
It drives all growth and all down stream nutrient uptake.
If you have low limiting nutrients, that influences CO2 demand, the CO2 is no longer limited at higher NO3 or other nutrient levels.
Bobbing between limitation and non limiting nutrient levels has a large effect on CO2 demand.
Not acknowledging this is a common mistake done by aquairsts, and many should cetainly know better.
To set upo any basic experiment where you are testing a particularly parameter of interest, you need to ensure that there is independence and that the dependent variable, say K+ is the only one that might be excess or limiting during the test run.
I've yet to see any aquarist do this when they claim such and such nutrient has some "special effect" on some plants.
It's easy to disprove.
All I have to do is grow the same plant at those levels in good nice form the falsify the hypothesis.
Ive done many times.
Pissed a few folks off that where, and a few still are, certain of their results.
But I'd rather be correct than making friends with folks who cannot see things critically nor acknowledge the faults.
I make lots of mistakes, that's how I learn, but I do not keep doing the same ones over and over............
I've grow these plants at higher CO2 and higher nutrient levels without issues, not once etc, but for years............I can also induce thes same traits and issues with CO2 variaton as well as algae..........
Observations are fine etc, so is testing, but design the test to answer the question you have!
This takes more thought. This is the creative side of sceince.
And how to do it cheaply or easily is another idea to consider.
Longywalker got it and figured it out.
CO2 and light..........
I have a nice stand of A reineckii, I've always considered it one of the easier red plants around.
M umbrosum is an infernal weed.
Both should pearl agressively and be fine over a wide range if the CO2 is good, like most plants. I've also grown these plants in non CO2 neglected tanks just fine.
Spending all this effort for measuring NO3 is fine, however, folks are not nearly as accurate when it comes to CO2, and flow rates, filter clogging, plant biomass changes through time, all of which influence CO2 to the plants.
It's not this nice simple thing like some suggest.
The underlying reason might be, but the gas exchange and boundary layers, flows etc play huge roles.
Light drives CO2 demand which drives NO3 uptake which drive sK+ and PO4 uptake etc.
If you limit PO4, then that downregulates the uptake of NO3/NH4/CO2 and light use efficiency. Ole and Troels did any experiement at tRopica detailing some of the CO2-light dynamics.
Any quick Google scholar search shows limiting Carbon will downregulate N uptake in plants and vice versa.
But what the heck do I know?
I've seen similar topics going back two decades and similar wrong conclusions which the data and test do not support. I knwo they do not because I have tanks with these parameters and no stunting.........however the CO2 is higher and I watch the plants first, then test.
I look for success, then I try to mess it up from there.
If I have excellent growth at a particular CO2 level, then I add lots of KNO3, PO4 etc, and I still have excellent growth, what does that suggest vs this test?
Confounding factors. I can repeat this test as I have for most of a decade now with these plants in question..........
I have lab grade test methods and good methodology, as well as lab equipment. Girlfriend complains about the home "lab".