Sure, if you assume those readings to be correct for all times during the week, dosing etc.
Also, think about 50% weekly water changes and adding some Mg/Ca back each time, we do not know what Mg and Ca are in the tap water he uses or not...........
So that's an unknown, nor do such supply stay stable, they might be much higher than anyone realizes.
Also, the CEC effects from the clay sediments used, ADA, binds the Ca and Mg.
So while it might not be present in the water column, the bacteria and plant roots can still have access to it.
So water column measurements for nutrients is really not that relevant,
it's only 1/2 the picture here.
Something some folks seem to want to and in some cases actively chose to ignore.
This not only applies to Ca and Mg, it applies to NO3, PO4, Fe etc.
Using both water column and sediment dosing allows you to better supply nutrients both with respect to the human factor(who hasn't spaced out and forgotten to dose the water column a few times?) as well providing both locations for the plants to grow best.
Rate of growth is another issue, but ADA uses less light to do that and if they do use a lot of light, it ain't for long.
This is not modeled at all after nature as claimed, rather, practical experience.
If you model it after nature, then the light should be about 2-6X more and for the full 12 hours with full 10-12w/gal on HQI for no less than 8-10 hours per day.
That is the equivalent measure from the regions where the plants grow and live.
So with less light= less CO2 demand= less nutrient demand=> less reliance on higher dosing levels and more time for assimilation. Basically it's much easier to grow plants slower than faster.
The other real issue here/question is: why do you want 20ppm of GH?
What good is it to go so low?
Do fish prefer it?
Do plants prefer it?
Are their any negative effects at higher levels?
None anyone's seen or shown that I know of.
Showing that to be the case is a rather difficult proposition.
Especially when I keep altums at 50ppm.
And any plant species..........
So do other folks and they have for many years.
That is the control test that falsifies such a hypothesis.
So the burden of proof, is to show that these observations and results are false, a rather tough prospect
So the real question is why should we go to such lengths to replication a method?
Why would it be so fragile that we have to do such parameters?
Shouldn't plants, fish etc be able to tolerant a much wider range?
Most of the aquatic plants are weeds.
Most tropical fish are fairly hardy.
So yes.
It's fine to be curious, but I think many thing they will find nirvana by having some parameter, rather than good basic care, good routine maintenance etc. Old timer aquarist often tell folks this, but many do not listen, believing they have everything in place.
I led the low GH challenge maybe back in the late 1990's.
Others tried it, with Discus, various so called soft water plants, R macrandra etc and only ended up with better colors, healthy growth, good fish health.
If you add the pH/KH measurements on the ADA's parameter listing, they are functionally impossible.
You can have interference from the CO2 appearing too high relative to those parameters, but never the reverse that I am aware of.
So I hold a lot of suspect for that data.
If someone can explain how someone can have a KH of 2 and pH 6.9 and a CO2 of 15ppm, I'm all ears.
And every tank has the same data, which if you keep many tanks, you know is rather unlikely(and the parameters change through time as well). Seems like they fudged some data to me to say what folks would like to see/read/here.
But we can go to an ADA store, and measure the parameters and find they are not as stated..........
We have such a store here.
ADA is about selling their product. Keep that in mind, marketing is "perception".
Amano has a business to run. But he promotes the hobby well and to a higher level in doing so. So that is admirable. I like their products and look, the ADA As is great. But some of the things are not really jiving well.
An exmaple is the Tourmaline business, this is poppy cock.
CO2 levels with the KH/pH's.
All the tanks always reporting the same parameters
Etc.
I do not ask anyone to use belief, I'd rather see folks question things for themselves and see if it makes sense or not. Just make sure you have controls in place to make sure the results are something you can talk about and discuss.
That's just basic logic, philosophy etc.
Regards,
Tom Barr
Regards,
Tom Barr